module 5 -8

Module 5

Introduction

In this module, you will learn about prefixes and how to use them to indicate numbers, quantities, positions, directions, and negation. You'll practice using these and other prefixes with familiar word parts to build new terms. Exercises in this module may require you to review the structure of medical terms introduced in Module 1.

Remember that this integrated learning program is intended as a supplement to your text—not as a substitute. Be sure to keep your text available for ready reference.

Objectives

In this module, you will learn to:

• Match prefixes with their meanings.
• Recognize prefixes in terms and write their meanings.
• Use prefixes to build and analyze terms.
• Use a- or an- correctly to write terms of negation.

1.1 mono-, uni-

Recall from Module 1 that a prefix is a word part attached to the beginning of a term to modify its meaning.

In this lesson, you will learn prefixes that are used to indicate number or quantity. These prefixes have the same meanings in conversational English, so they will be familiar to you.

Two prefixes, mono- and uni-, are used to indicate the number one, and both can also mean single or alone. For example, monaural means pertaining to one ear; a monaural hearing aid is one designed for use with just one ear. Monoplegia means paralysis of one limb.

Uni- is more commonly used in conversational English. You are familiar with the terms unite, to become one, and uniform, meaning one shape or one appearance. Unilateral means pertaining to one side; a unilateral condition is one that affects only one side of the body.

1.2 bi-, di-, diplo-

The prefixes bi- and di- refer to the number two; these prefixes sometimes have the similar meanings of twice or double. Just as unilateral means one side, bilateral means two sides or both sides.

The suffix -para means to bear or to bring forth (live births), so bipara refers to a woman who has given birth twice. The bicuspid valve of the heart is the valve that has two cusps, the pointed, leaf-like structures that make up the valves.

Diencephalon, with the di- prefix to mean two, refers to the second portion of the brain, the portion between the mesencephalon and the cerebrum.

Be careful when applying meaning to this prefix because there are several other word parts with different meanings that begin with the letters d and i. Dia-, for example, means through.

A related prefix is diplo-, meaning double. You will recall from Module 4 that -opia means vision. Therefore, diplopia means double vision.

1.3 tri-

The number three is indicated by the prefix tri-. This is easy to remember when you consider that a tricycle has three wheels.

Just as the term bipara refers to a woman who has had two complete pregnancies, tripara indicates a woman who has given birth to three viable offspring from three separate pregnancies.

1.4 quadri-, tetra-

The number four is indicated by these prefixes: quadri- and tetra-.

Perhaps you are familiar with the term quadrennial, which means every four years. For example, in the United States we have quadrennial presidential elections. Recall that -plegia means paralysis. Therefore, quadriplegia means paralysis of all four limbs. The term tetraplegia has the same meaning but is less commonly used.

The tetralogy of Fallot is a congenital abnormality of the heart that consists of four specific defects.

Tetramastia is a condition characterized by the presence of four breasts. This is not a particularly unusual occurrence. The anomalous breasts are usually small and located above the normal breasts near the axillae (armpits).

Tetralogy of Fallot (TOF) occurs in approximately 3 to 6 of every 10,000 births and represents 5-7% of congenital heart defects. This condition was first described in the 1600s. It is named for Etienne-Louis Arthur Fallot, who accurately described the four pathologic characteristics of this condition in 1888.

1.6 centi-

The prefix centi- is related to the number 100 and may mean either one hundred or one-hundredth. Obviously, these meanings are very different, so it is important to use caution when you interpret this prefix.

You are familiar with the term centennial, which means pertaining to 100 years. You may recall the term centigrade from Module 4, referring to the Celsius temperature scale and meaning 100 degrees, the number of degrees between the freezing and boiling points of water on this scale.

More commonly, centi- means one-hundredth and is applied to measurement units in the metric system. For example, a centimeter is one one-hundredth (1/100) of a meter, and a centigram is one one-hundredth of a gram.

1.7 milli-

The prefix milli- means one-thousandth.

This prefix also is applied to measurement units in the metric system. For example, a millimeter is one one-thousandth (1/1000) of a meter, and a milliliter is one one-thousandth of a liter.

1.9 primi-

The prefix primi- means first. This should be easy to remember because you are familiar with the words prime and primary, which mean first and pertaining to first, respectively. For example, prime quality means the first or highest quality. Your primary objective is your first or most important goal.

Examples in medical terminology include primigravida, meaning pregnant for the first time, and primipara, referring to a woman who is experiencing her first delivery.

1.10 hemi-, semi-

Although hemi- usually means half, and semi- more often means partly, both prefixes may have both meanings. Consider the following common examples of terms that employ these prefixes.

hemiplegia: half paralysis; paralysis of both the arm and leg on one side of the body

hemithorax: half of the chest, referring to either the left or right side

hemianopsia: loss of half of the field of vision, often as a result of a stroke

semiconscious: partly conscious; not fully aware

semirecumbent: partly lying down; lying down with the head and shoulders elevated

These prefixes are similar to word parts that have other meanings. Note the similarity between hemi- and hem/o, meaning blood. Take care not to confuse semi- with the combining forms semin/o, meaning semen, and semi/o, meaning sign.

1.11 hyper-, hypo-

Two very common prefixes in medical terminology are hyper- and hypo-.

Hyper- means excessive or more than normal. Hypertension is the term for high blood pressure, specifically a measurement that is persistently above 140/99 mm Hg. You will recall from Module 4 that hyperthermia, meaning excessive heat, is a term for fever. Can you form a term that means excessive movement?

Hypo-, on the other hand, means beneath or below, or less than normal. An easy way to remember is to note that the final letter "o" rhymes with low.

An example of this suffix meaning beneath is the term hypogastric, meaning beneath the stomach. An example of hypo- meaning below normal is hypoglycemia, the term for an abnormally low concentration of glucose in the blood.

Note that while hyper- and hypo- are used to refer to above and below normal quantities, respectively, only hypo- is used to refer to location. That is, hypo- can mean beneath, but hyper- does not mean above except in the sense of above normal.

1.12 pan-, nulli-

If you guessed either hyperkinesia or hyperkinesis as the term for excessive movement, you are right!

The prefix pan- means all. You will recall from Module 4 that sinusitis means inflammation of the paranasal sinuses. When all four sets of sinuses are involved, the term for this condition is pansinusitis.

The prefix nulli- means none. Thus, nulligravida refers to a woman who has never been pregnant, and nullipara indicates a woman who has never given birth to a viable offspring.

The prefix nulli- is related to the word null. In mathematics, null means equal to zero. In law, null means not legally valid or of no value.

1.13 multi-, poly-

Two prefixes mean many: multi- and poly-.

Multipara, for example, refers to a woman who has given birth to viable offspring more than once.

Multiple myeloma literally means many bone marrow tumors. It is the term for a malignant disease of the bone marrow that interferes with normal bone marrow functions, destroys osseous tissue, and leads to pain, hypercalcemia, fractures, and skeletal deformities. It typically occurs at many sites at the same time.

Perhaps you remember the term polycythemia from Module 4. This is the term for an increased number of (many) erythrocytes in the blood. Polycystic means containing or composed of many cysts.

1.14 super-, ultra-

Super- and ultra- can both mean either beyond or excessive. In Module 3, you learned that ultra- means beyond and ultrasound means sound that is beyond normal hearing range. Super- means beyond normal in words like supernatural.

With respect to quantity, both prefixes mean excessive or great amounts. Supervitaminosis, for example, is a condition of excess accumulation of vitamins in the body due to overdose. Superannuated means characterized by an excessive number of years; that is, very old.

An ultramicrobe is a microorganism that is excessively small, too tiny to be seen with an ordinary microscope.

2.1 ab-, ad-

The prefixes ab- and ad- are similar to each other but have opposite meanings. Ab- means away from and ad- means toward.

As shown in the illustration, abduction means drawing away from the midline, and abductor muscles are those that accomplish this movement. Adduction means drawing toward the center and is performed by adductors.

Other examples include abneural and abnerval, both meaning away from the nerve; likewise, adneural and adnerval mean toward the nerve.

2.2 ante-, pre-

The prefixes ante- and pre- mean before, referring to either time or location. With respect to location, both prefixes mean in front of.

Thus, antenatal and prenatal both mean pertaining to the time before birth. Prenatal vitamins, for example, are those formulated to be taken during pregnancy.

The antecubital fossa is the hollow area in front of the elbow. The prevertebral space is the area in front of the vertebrae, the bones of the spine.

2.3 circum-, peri-

Two prefixes are used to mean around or surrounding: circum- and peri-.

Circumduction is the term for circular movement of a limb or of the eye. Circumcision means to cut around and is the term for the surgical removal of all or part of the prepuce, or foreskin.

You will recall from Module 2 that a perinatologist specializes in the care of mother and child during the time surrounding the birth.

The pericardium is the membrane that surrounds the heart.

2.4 dia-

In the previous lesson, you were cautioned not to confuse the prefix di-, meaning two, with dia-. Dia- is the prefix that means through.

Diarrhea, for example, literally means flow through. It is the term for an abnormal liquidity and frequency of fecal discharges.

Diathermy means the process of heating through and refers to the heating of body tissues for therapeutic purposes by use of electromagnetic radiation, electric currents, or ultrasonic waves.

2.5 ecto-, ex-, exo-, extra-

The similar concepts of out, outside, without, or away from may be indicated by any of these prefixes: ecto-, ex-, exo-, or extra-. Consider the following examples, some of which should be familiar to you.

ectopic: away from the normal location; situated in an unusual place
For example, an ectopic pregnancy is one that occurs outside the uterus.

exangia: the condition of dilation or bulging out of a blood vessel; aneurysm

exostosis: benign growth projecting outward from the surface of a bone

extracorporeal: situated or occurring outside the body

extraocular: situated or occurring outside the eye

2.6 en-, end-, endo-

Opposite in meaning to the prefixes on the preceding screen are these that mean inside or within: en-, end-, and endo-.

You will recall that cephal/o is the combining form for head, so now it should be clear to you why encephal/o is the combining form for brain. The prefix en- means within and the brain is the structure within the head. Similarly, encranial means within the cranium, the bones of the skull.

Terms with the prefix end- include endarterial, within an artery, and endangium, the innermost lining membrane of a blood vessel.

Endo- is part of endocardium, the lining of the inner surface and cavities of the heart. Perhaps you recall from Module 2 that an endodontist is a dentist who specializes in treating conditions of the pulp and root of a tooth, that is, the structures inside the tooth.

2.7 epi-

The prefix epi- means above, upon, or on. Epiglottis means above the tongue and is the term for the lid-like structure that overhangs the entrance to the larynx and prevents food from entering the larynx and trachea while swallowing.

As seen in this illustration, the dermis is a deep layer of the skin, consisting of a bed of vascular connective tissue. Epidermis means above the dermis and is the term for the outermost avascular (without blood vessels) layer of the skin, composed of an outer, dead part and a deeper, living part.

2.9 infra-, sub-

In the previous lesson, you learned that hypo- can mean beneath or under. Two other prefixes also have this meaning: infra- and sub-.

Infrapatellar, for example, means below the patella, the kneecap. Subpatellar has the same meaning but is less commonly used.

Submandibular means under the mandible, the lower jaw. The submandibular glands are a pair of salivary glands that secrete saliva into the mouth.

2.10 inter-, intra-

These two prefixes appear similar, and occur in similar terms, but have quite different meanings. Inter- means between, and intra- means within or into.

Since these prefixes are used in conversational English, it may help you to relate them to more familiar terms. Intercollegiate means between colleges, so an intercollegiate contest or game would be a competition between one college and another. Intramural, on the other hand, means within the walls and refers to a game or contest between students who attend the same school.

In medical language, inter- is found in such terms as intercostal, meaning between the ribs, and interocular, meaning pertaining to, or situated between, the eyes.

Two terms that refer to sites for medication injections use the prefix intra-. Intramuscular means within the muscle, and intravenous means within a vein.

2.11 ipsi-, contra-

The prefix ipsi- means same, and the most common application of this word part is in the term ipsilateral, meaning pertaining to, situated on, or affecting the same side. For example, if a patient were struck on the right side of the head and had pain on the right side of the head, we might say he had ipsilateral pain.

The prefix that means opposite is contra-. Contralateral means pertaining to, situated on, or affecting the opposite side. If the patient with the right-side head injury experienced pain on the left, that would be contralateral pain.

2.12 meso-, mid-, medio-

Meso-, mid-, and medio- are prefixes that mean middle. Medial means pertaining to the middle and is used to describe the location of a structure that is in, or near, the midline of the body. Mesosternum is a term for the gladiolus, the middle portion of the sternum, the breastbone.

The middle of many structures is indicated by the prefix mid-. Midclavicular, for example, means pertaining to the middle of the clavicle, or collar bone, and midline refers to the center line of the body or of a structure.

Mediolateral refers to the direction from the middle to the side. This term is used to describe x-ray projections where the beam enters a body part on its medial aspect and exits on the lateral (side) aspect.

2.13 para-

The prefix para- has two meanings. It can mean near or beside as in paranasal, near the nose. A paranasal sinus is an accessory cavity in the bones surrounding the nose. Pararenal means near the kidney, and parasternal means beside the sternum.

The other meaning of para- is abnormal. Parasecretion, for example, means to secrete abnormally or refers to a substance that is abnormally secreted. Parapsia is an abnormality of the sense of touch.

2.15 per-

The prefix per- means through or by, in the sense of by way of.

One term with this prefix is permeable. This term describes a membrane or substance that is capable of allowing a fluid to pass through it.

Another example, percutaneous, describes a procedure performed through the skin. Several specific procedures include this term in their titles, such as:

percutaneous coronary intervention (PCI): a nonsurgical intervention for treatment of coronary artery disease in which a catheter is threaded into a coronary artery; access to the artery is gained through a needle that is passed through the skin

percutaneous transhepatic cholangiography (PTC): an imaging procedure where contrast material is injected via a needle passed through the skin, through the abdominal wall, through the liver, and into the common bile duct to allow diagnostic imaging, cytologic sampling, dilation of narrowed areas, or removal of stones

2.16 post-, retro-

The two prefixes, post- and retro-, both mean behind. For example, postclavicular means located or occurring behind the clavicle, and retronasal means behind the nose.

But there can also be subtle differences in the meanings of these word parts. Post- often means after or following as in postpartum, after childbirth, and postictal, which means after a seizure or following an attack.

Retro- can also mean backward. For example, retrograde means moving or flowing in the direction opposite that considered normal. A retrograde pyelogram, also called a retrograde urogram, is an x-ray examination of the urinary tract obtained after a contrast medium is injected through catheters placed into the ureters through a cystoscope. It is called retrograde because the contrast flows in the direction opposite the direction of the normal flow of urine.

2.17 supra-, super-

Supra- means above. This prefix is found in suprapatellar, meaning above the kneecap, and suprapubic, which means above the pubic bone. Thus, a suprapubic prostatectomy is the surgical removal of the prostate gland performed through an incision above the pubic bone.

In Lesson 1 of this module, you learned that super- is a prefix that means excessive, but super- can mean above as well. Superior means situated above or directed toward a higher place. This term is used to refer to a structure located nearer the top of the head. For example, the hip is superior to the knee and the nose is superior to the chin.

2.19 sym-, syn-

Both sym- and syn- mean joined, together, or with. For example, syndactyly, illustrated here, is an anomaly of the hand or foot marked by the joining of fingers or toes. Syndactyly may range in degree of severity from incomplete webbing of the skin between adjacent digits to the complete union of digits and fusion of the bones and nails.

Symphysis literally means growing together and is the term for a type of joint in which adjacent bony surfaces that are separate in early development unite firmly to form a fibrocartilaginous joint. A good example is the symphysis pubis, the midline joint between the right and left pubic bones.

2.20 trans- (animation)

The final prefix in this lesson is trans-, meaning across or through. This prefix is common in conversational English in such terms as transport (to carry across), transmit (to send across), and transfer (to bear across). Consider the word transmission, the process of passing, or transferring, a disease from one person to another. The germs or infectious agents pass through certain barriers of a second, healthy person, as the animation demonstrates.

Medical terms with this prefix include transdermal, meaning across or through the skin. For example, transdermal therapeutic system is the term for a medication applied to the skin in a paste form on small adhesive disks. The medication is absorbed through the skin into the bloodstream. One such topical drug, nifedipine, is used by patients with heart conditions to increase vascular dilation. Other examples include the transdermal nicotine patches used to treat symptoms of nicotine withdrawal when quitting smoking and adhesive scopolamine disks to treat vertigo and to prevent motion sickness.

Other medical examples of the prefix trans- include transthoracic, through the chest, and transvaginal and transurethral, referring to procedures performed through or across the vagina and the urethra, respectively.

3.1 a-, an-

In this lesson, you will learn more prefixes. Although many of them will be familiar to you from previous lessons, be alert for some new meanings and applications.

First, we will consider prefixes that indicate negation. The prefixes a- and an- both mean no, not, or without. The prefix a- is used when the following letter is a consonant, and an- is appropriate when followed by a vowel.

You will recall that -phasia means speech. Thus, aphasia means without speech and refers to a disorder marked by a loss or defect in the ability to speak.

The combining form ox/o means oxygen and the suffix -ia means condition. These word parts can be combined with a negative prefix to create a term that means without oxygen:

an- + ox/o + -ia = anoxia

Recall from Module 4 that anoxia causes cyanosis, a blue coloration of the skin and mucous membranes.

3.2 in-

Another prefix related to negation is in-. In- means not, as in incompatibility, not compatible, unable to coexist in harmony, or the quality of being ill-suited for combination or simultaneous administration. For example, drugs that are incompatible must not be given together.

Another familiar term with this prefix is incoherent. Coherent means having an orderly continuity or proper sequence or refers to a person who is able to express ideas in a logical, intelligible manner. Thus, incoherent means not logical or intelligible, or unable to express oneself coherently.

In- can also be used to denote in, inside, or within. Ingestion, for example, means the process of taking into the mouth as food.

3.3 megalo-, macro-, mega-, micro-

The following prefixes are related to size.

You will recall from Module 4 that -megaly means large, so it will be easy for you to remember that megalo- also means large. The prefixes macro- and mega- also mean large.

You should also recall from Module 4 that pod/o means foot. Thus, macropodia is the condition of abnormally large feet.

Megalocyte and macrocyte are both terms that refer to abnormally large red blood cells that are seen in certain types of anemia. Megacephalic and macrocephalous are both terms that denote an abnormally large head.

The prefix micro-, on the other hand, means small. You are familiar with the term microscope, an instrument with lenses for viewing objects that are very small. Microcephaly is a congenital defect marked by abnormal smallness of the head, commonly associated with mental retardation.

3.4 pro-, post-

You have already learned that ante- and pre- can mean before. For example, antepartum and prenatal both mean before birth. Antepartum is usually applied specifically to the maternal process of giving birth, whereas prenatal more often refers to the process of being born.

Pro- also means before. A prodrome is a symptom or set of symptoms that occurs before the manifestation of a disease. For example, some patients can sense a prodrome that predicts the onset of a migraine headache or an epileptic seizure.

Also related to time is the prefix post-. You will recall from the previous lesson that this prefix means behind but can also mean after, as in postpartum, after childbirth, and postmortem, meaning after death. A postmortem examination includes dissection of internal organs and structures and is performed to determine the cause of death; it is also called an autopsy.

3.5 anti-

In Lesson 2 of this module, you encountered the prefix contra- meaning opposite. Contra- can also mean against as in contraceptive, meaning preventing or diminishing the likelihood of conception. The term contraceptive can also refer to an agent that prevents or reduces the chances of conception.

The prefix anti- also means against. Antibacterial, for example, means destroying or inhibiting the growth or reproduction of bacteria. Antibacterial can also refer to an agent that kills bacteria or inhibits their growth or reproduction. The names of many drug classes begin with anti- because their purpose is to act against a particular agent or problem. Examples include antiasthmatic, antianxiety, and antianginal.

3.6 brady-, tachy-

You may recall from Module 4 that bradyphasia means abnormally slow speech. From this you can identify that brady- means slow. Tachy- has the opposite meaning: fast. Tachycardia refers to an abnormally fast heartbeat, more than 100 beats per minute. Bradycardia is a slow heartbeat, less than 60 beats per minute.

The suffix -pnea means breathing. When combined with these prefixes, the terms bradypnea and tachypnea mean slow breathing and rapid breathing, respectively.

3.8 dys-, mal-

The prefix dys- means bad or difficult and can also denote painful or abnormal. Dyspnea, therefore, means difficult breathing, and dysmenorrhea means painful menstruation. Dyspepsia means impairment of digestive function; it is a synonym for indigestion. This is a very common prefix. You may find it interesting to check the glossary or your medical dictionary for a list of terms that begin with dys-.

Another prefix that means bad or abnormal is mal-. Malnutrition, for example, means bad or poor nutrition and may apply to any nutritional disorder. Malocclusion, illustrated here, refers to abnormal contact between the teeth of the upper jaw and those of the lower jaw so as to interfere with chewing. Malocclusion is an important reason for pursuing orthodontics, which, as you will recall from Module 2, refers to dental treatment for the straightening of teeth.

3.9 eu-

The prefix eu- means good or normal. For example, the term euthyroid pertains to a normal thyroid gland.

Eupnea literally means good breathing and refers to normal, easy respiration. Eupepsia refers to normal, healthy digestion. Euphoria is derived from Greek roots that mean "to carry well" and refers to an exaggerated sense of physical and emotional well-being.

4.1 Abbreviations in Prescriptions Denoting Time and Frequency

The abbreviations in this lesson stand for Latin words that are used in writing prescriptions and sometimes for making notations in medical charts.

Prescriptions usually state when a medication should be taken with regard to meals because some medications can upset the stomach if taken when the stomach is empty. Others must be taken on an empty stomach for proper absorption or so as not to interfere with digestion.

Prescriptions may also state the frequency with which a medication should be administered.

The following table provides a quick reference of standard prescription abbreviations, along with their Latin origins, denoting time and frequency for administration of a prescribed medication.

ABBREVIATION	MEANING	LATIN ORIGIN
a.c.	before meals	ante cibum
p.c.	after meals	post cibum
b.i.d.	twice a day	bis in die
t.i.d.	three times a day	ter in die
q.i.d.	four times a day	quarter in die
noct.	night	nocte
b.i.n.	twice a night	bis in noctis
ad lib.	freely, as desired	ad libitum
p.r.n.	as needed	pro re nata
q.	every	quaque

4.2 More Prescription Abbreviations

The Latin word for water is aqua, abbreviated aq. What is meant by a physician's order to administer aq. ad. lib.?

Good for you if you knew that aq. ad. lib. means to give water freely!

Many medications are administered by mouth. The abbreviation for by mouth is PO, for the Latin per os.

If the patient is allowed nothing by mouth, the abbreviation is NPO, for the Latin nil per os.

Our final abbreviation is used in an urgent situation when orders may be marked stat. This is the Latin abbreviation for statim, meaning immediately.

If you've studied the combining forms, suffixes, and prefixes in your text, you're now ready for the additional practice you'll receive with terms and abbreviations you've learned in this module. Check your glossary for definitions of all the word parts used in the following exercises. To review construction of medical terms using prefixes, combining forms, and suffixes, return to Module 1. Click Next to continue.

Module 6

Introduction

In this module, you will learn terms associated with the body's structure and organization. You'll also learn about medical terms used to designate position, direction, and location. You'll continue to develop an understanding of drug classes, uses, and effects. Exercises in this module may require you to review the structure of medical terms introduced in Module 1.

Remember that this integrated learning program is intended as a supplement to your text—not as a substitute. Be sure to keep your text available for ready reference.

Objectives

In this module, you will learn to:

• Recognize the relationship of cells, tissues, and organs.
• Name four main types of tissue.
• Recognize directional terms and planes of the body.
• Identify the body cavities.
• Compare the two systems of identifying abdominopelvic regions.
• Identify the four abdominal quadrants.
• Identify the nine abdominopelvic divisions used by anatomists.
• Write the meanings of the word parts and use them to build and analyze medical terms.

1.1 Atoms

This lesson will introduce you to the building blocks of the body, from the tiniest particles to the living body as a whole.

On a chemical level, the basic building block of the universe, including human beings, is the atom. This term combines a-, without, and tom/o, meaning to cut. The atom is so named because, at the time the term was established, it was thought that atoms could not be divided into smaller parts. Although we now know that atoms may be split and that they can contain as many as 100 different subatomic particles, the smallest particle of any substance that contains all the characteristics of that substance is the atom.

A substance that contains only one type of atom is called an element. The body is made up of many elements including hydrogen, oxygen, carbon, nitrogen, and calcium.

1.2 Molecules

The combination of two or more atoms is called a molecule. Molecules form substances that are quite different from the elements that compose them. For example, hydrogen and oxygen are gases, but they combine to form water. The chemical symbol for water, H₂O, indicates that it is made up of two atoms of hydrogen and one atom of oxygen. Water molecules make up more than half of the total body weight of most individuals.

Many other molecules are also present in the body, including various sugars and salts. Substances composed of molecules are called compounds.

Portions of molecules or atoms that are incomplete and therefore carry an electric charge are called ions, the term for charged particles.

1.3 Cells

The basic building block of all living things is the cell. There are many different types of cells, but most have some of the same basic characteristics. All have an outer membrane and contain specialized structures with specific functions that are referred to as organelles. As the name implies, you can think of organelles as small organs. The organelles are suspended in a liquid called cytoplasm.

For example, the nucleus of the cell is the organelle that contains the chromosomes. These thread-like structures are composed of a special protein called DNA (deoxyribonucleic acid) in specific configurations called genes. The genes determine the characteristics of the individual and the functions of the cell. The term that means pertaining to genes is genetic.

The DNA transmits genetic information from one generation to the next. Genetic diseases are those that are congenital, which literally means pertaining to with genes. Congenital refers to conditions that are present at birth.

1.4 Stem Cells

Life begins with a fertilized egg, which proceeds to divide and multiply, creating more and more cells that eventually develop into a mature individual. During development, cells become specialized for their specific functions. Cells that have the ability to divide without limit and give rise to specialized cells are called stem cells.

1.6 Tissues

A group of similar cells that function as a unit is called a tissue. There are four basic tissue types:

epithelial tissue: tissue that forms the covering of body surfaces. Epithelial tissues include the skin that covers the outer surface and the mucosa, the mucous membrane that forms the covering of inner surfaces such as the inside of the mouth and the digestive tract.

connective tissue: tissue that binds and supports other body tissue and parts, such as bone and cartilage.

nervous tissue: tissue that makes up the brain, spinal cord, and nerves; nervous tissue conducts messages to and from the brain and other parts of the body. The nervous tissue controls and coordinates many body activities.

muscle tissue: tissue that produces movement. Skeletal muscle (striated or striped) tissue produces voluntary movement of the body; smooth muscle tissue produces the involuntary movements of internal organs such as the stomach. Cardiac muscle is a specialized tissue that forms the basic structure of the heart.

1.7 Organs

Groups of tissue types that combine to form a more complex structure, and work together to perform specific functions, are called organs. You are familiar with many organs, such as the heart, the liver, the kidneys, and the lungs. The largest organ of the body is the skin, which is not commonly thought of as an organ, but which precisely fits the definition.

1.8 Body Systems

A body system is a group of several organs that work together to accomplish a set of related functions. For example, the urinary system consists of the kidneys, ureters, and bladder. It functions to remove waste products and excess fluid from the blood and excrete them from the body as urine.

There are eleven body systems that have specific roles in the function of the body as a whole. They are listed and described in your text in Table 6-1 (pg. 83 in your text). Each system will be considered in detail in Modules 8 through 17.

1.9 The Body

Together, the body systems and their component parts—the organs, tissues, and cells—make up the living, functioning body. The combining forms for body are som/a and somat/o; the term that means pertaining to the body is somatic.

Somatic cells are all the cells of the body with the exception of the sex cells, the male sperm and the female ova. Somatic cells have 46 chromosomes in 23 pairs. Sex cells have only 23 chromosomes, which are not paired. They become paired when combined with each other at conception.

2.1 Positioning Terms for Medical Treatment

Medical treatment often requires a patient to be arranged or placed in a certain posture or position. For example, specific positions may be used to promote healing, to reduce the risk of medical complications, or to produce an x-ray image of a particular organ. Medical professionals use specific terms to communicate clearly about directions and body positions.

2.2 Body Structure Relationships

Similarly, special terms are used to describe the location or spatial relationship of one bodily structure to another. Instead of saying that the intestines are below the stomach or that the heart is between the lungs, we use specific medical language to help define these relationships.

2.3 Threaded Case Study: Karen

As we try to understand how these medical terms are used, let's meet Karen Ross. Karen wants to begin an exercise regimen to improve her fitness. She's decided to visit Dr. Likens for a routine physical exam before she begins her new program. Let's see how some of our terms are used during the course of Karen's exam.

2.4 Anatomic Position

When directional terms are applied, it is assumed that the body is in the standard neutral position of reference known as the anatomic position. In this position, the body is in an erect, or standing, posture, facing directly forward, with the arms hanging down at the sides and the palms facing forward.

2.5 Body Planes

Body planes are imaginary lines that divide the body into sections, providing another type of orientation to its structure and organization. There are three major planes that lie at right angles to one another: the frontal or coronal, sagittal, and transverse.

The frontal/coronal plane is a lengthwise vertical plane that divides the body into anterior and posterior portions. The sagittal plane, running lengthwise from front to back, divides the body into right and left portions. If a sagittal section is made in the midline, it is called a midsagittal plane. The transverse plane runs horizontally through the body, dividing it into upper (superior) and lower (inferior) parts.

2.6 Anterior, Ventral

Many of the terms used to identify body directions are constructed from word parts. The term anterior is built from the combining form anter/o—meaning front—and the suffix -ior, which means pertaining to. Thus, the definition of anterior is pertaining to the front.

The combining form ventr/o means belly or front. When joined to the suffix -al—pertaining to—the word ventral is formed, meaning pertaining to the belly or front. When referring to humans, the terms anterior and ventral are used interchangeably.

2.7 Threaded Case Study: Karen

Posterior—built from the combining form poster/o, meaning back or behind, and the suffix -ior—is defined as pertaining to the back.

To designate a location that is on the outer side of a posterior surface, we use the term posteroexternal. Posterointernal, on the other hand, describes a location that is within and toward the back.

To appraise Karen's ability to begin her new fitness program, Dr. Likens will conduct a thorough inspection of Karen's posture and skeletal alignment from both anterior and posterior views.

2.8 Terms Related to Radiographic Projections

When necessary, more specific directional information can be provided by constructing a single term from two combining forms. Remember, at the beginning of this module, we mentioned that directional terms are used in radiology. In that setting, directional terms indicate the path of the x-ray beam, indicating by the order of the word parts which aspect of the body will be struck first by the x-ray beam. For example, the term posteroanterior, abbreviated PA, tells us that the x-ray will travel from back to front as in the top figure.

Anteroposterior, abbreviated AP, informs us that the source of the x-ray is in front of the body and that the beam will exit from the back (bottom figure).

2.9 Dorsal, Dorsoventral

The term dorsal, built from the combining form dors/o, which means back, and the suffix -al, is often used as a synonym for posterior. And just as we joined two combining forms to create the term posteroanterior, we can construct a like term—dorsoventral—by joining the combining forms dors/o and ventr/o and adding the suffix -al. Dorsoventral is also defined as pertaining to the direction from the back to the front.

2.10 Lateral, Dorsolateral

Lateral, which contains the combining form later/o, meaning pertaining to the side, indicates a direction that is away from the body's midline. If one body part is described as lateral to another, its relationship is to the side of that structure. For example, the lungs are lateral to the heart. The abbreviation for lateral is lat.

Dorsolateral combines dors/o and later/o to form a term that indicates a location that is both to the side and to the back, or at the side of the back.

2.11 Unilateral, Bilateral

Now let's add some prefixes to the term lateral to see how the meaning of the word changes.

You will recall from Module 5 that the prefix uni- means one. If we place the prefix uni- before the term lateral, we form the word unilateral, which you remember means pertaining to one side. In the accompanying illustration, we see the assessment of the extent of unilateral movement, abduction of a hip joint on the right side only.

Now, if we take the term unilateral and replace the prefix uni- with the prefix bi-, we form the word bilateral. Recall that bi- means two. Therefore, the assessment of range of motion on both the right and left sides would be a bilateral assessment.

2.12 Medial

The term medial means pertaining to the middle and may also be used to describe the location of a structure that is toward the midline of the body. For example, the nose is medial to the left eye.

Mediad, defined as toward the middle, refers to the direction from side to center. For example, the location of the umbilicus is mediad to the stomach.

You will recall from Module 5 that both medial and mediad are built on the combining form medi/o, which means middle.

2.13 Anteromedial, Anterolateral, Posterolateral, Posteromedial

As demonstrated earlier in this lesson, we can create specific directional terms by joining two combining forms. In this way, we form such words as anteromedial, defined as pertaining to the front and the middle, and posterolateral, pertaining to the back and the side.

Likewise, anterolateral means located on the front and the side, and posteromedial means near the back and the center.

2.14 Threaded Case Study: Karen

During Karen's physical examination, she and Dr. Likens will discuss her health history, her health habits, and her family's health history. Karen will be asked whether she smokes and what her previous level of exercise tolerance has been. Dr. Likens will gather additional information by listening to Karen's heart and lungs, moving the stethoscope systematically—laterally and medially—for a thorough assessment.

2.16 Superior, Inferior

As you will recall from Module 5, superior—a term that combines the combining form super/o and the suffix -ior—indicates a position that is above.

Anterosuperior, then, means above and toward the front. Another related term is superficial, which means on or near the surface or related to the surface.

Inferior, a combination of the combining form infer/o, which means below, and -ior, is the opposite of superior and refers to a position that is below.

The related terms inferomedial and inferomedian are used to indicate a location that is below and toward the midline.

2.17 Cephalad, Caudad

Cephalic—built from the word parts cephal/o, meaning head, and the suffix -ic, meaning pertaining to—may also be used to refer to a structure that is situated above another or nearer the head.

A related term, cephalad, ends in the suffix -ad; thus, cephalad is defined as toward the head.

Dorsocephalad is a related term that means toward the back of the head.

Caud/o is a combining form meaning tail or the lower part of the body. Thus, caudal, meaning below or nearer the feet or tail, describes an inferior position and is the opposite of cephalic.

Caudad literally means toward the tail. This term indicates a direction toward the lower part of the body and is the opposite of cephalad.

2.18 Proximal, Distal

The term proximal is formed by adding the suffix -al to the combining form proxim/o, meaning near. Proximal means near the point of attachment or origin. It describes the location of a structure in relation to the trunk of the body or to the structure's point of origin.

The opposite of proximal is distal, formed by adding -al to the combining form dist/o, meaning far. Distal means away from that point of reference. For example, the elbow is proximal to the wrist and distal to the shoulder.

Another combining form that means distant, far, or remote is tel/e. There are many familiar terms in conversational English that are based on this word part, such as telephone and television. A related medical term is telecardiogram, which refers to an ECG study that is recorded at a location remote from the patient by sending the electric signals over a telephone line.

2.19 Muscle Strength Assessment

In the accompanying illustration, muscle strength is being assessed. Notice that the doctor places one hand at the distal end of the forearm and the other hand near the elbow at the distal end of the upper arm. The doctor will evaluate muscle strength bilaterally.

2.20 Palmar, Plantar

Now let's consider another set of terms that refer to body surfaces. Remember that when a person is in the anatomic position, the palms—the somewhat concave part of the hand between the base of the fingers and the wrist—are facing forward. In other words, the palmar surface of the hands is showing, as in the illustration on the left.

A corresponding term, plantar, is used to refer to the sole, or undersurface, of the foot, seen in the illustration.

2.21 Supine, Prone

Supine and prone are terms that refer to specific body positions. To be in a supine position means to lie horizontally on the back. The prone position involves lying face downward.

Both the supine and prone positions are also considered recumbent positions; that is, the person is lying down. A person lying on one side would be said to be in the lateral recumbent position.

2.22 Supination, Pronation (animation)

Related to these descriptors are the terms supination and pronation.

Besides referring to the act of lying on the back, supination is also defined as a kind of rotating movement, such as that which turns the palm upward.

Similarly, pronation indicates the assumption of a prone position and also the downward and/or backward rotation of a joint, such as that which turns the palm downward.

3.1 Body Cavities

A useful way to consider body structure and learn its parts is to partition it into the internal spaces that contain the body's organs. These spaces within the body are known as the body cavities.

The body contains two major cavities, the dorsal and the ventral. The dorsal cavity is subdivided into the cranial and spinal cavities. The ventral cavity has three subdivisions: the thoracic, abdominal, and pelvic cavities.

3.2 Dorsal Cavity

Together, the cranial and spinal cavities form the dorsal cavity, so called because of its location at the back, or posterior, part of the body.

The cranial cavity contains the brain; the spinal cavity houses the spinal cord and the roots of the spinal nerves.

The term cranial is a combination of crani/o and -al, meaning pertaining to the skull, specifically that portion of the skull that contains the brain.

Likewise, spinal is a combination of spin/o and -al. It means pertaining to the spine.

3.3 Ventral Cavity

The ventral cavity consists of the thoracic, abdominal, and pelvic cavities, which are located at the anterior, or front, part of the body.

3.4 Thoracic Cavity

The thoracic cavity is the space between the base of the neck and a muscular wall, the diaphragm, which separates it from the abdomen. The thoracic cavity contains the lungs, the heart, and major blood vessels leading to and from those organs. It also contains other structures that are parts of the respiratory and digestive systems. You'll learn about these in later modules.

Thoracic is a combination of thorac/o and -ic. This term, therefore, means pertaining to the thorax or chest.

Perhaps you recall the term transthoracic, through the chest, from Module 5. In Module 3, you were introduced to the term thoracocentesis, a surgical puncture of the thorax to aspirate fluid. Other related terms include thoracotomy, an incision through the chest wall; thoracodynia, meaning chest pain; and suprathoracic, meaning above the thorax.

3.5 Abdominal Cavity

The abdominal cavity—the space between the diaphragm and the pelvic area—contains the stomach, small and large intestines, and other organs of the digestive and urinary systems.

This area is also referred to simply as the abdomen, abbreviated abd. The combining form that means abdomen is abdomin/o, and thus abdominal means pertaining to the abdomen.

Abdominoplasty is a term for a surgical procedure to tighten the abdominal muscles, in lay terms referred to as a "tummy tuck."

Abdominothoracic joins the combining forms for both abdomen and thorax to build a term that means pertaining to both the abdomen and the thorax.

3.6 Peritoneum

The wall of the abdominal cavity is lined by an extensive membrane called the peritoneum, which also enfolds the abdominal organs, the viscera (sing., viscus), and holds them in place. The combining form for viscera is viscer/o, and visceral means pertaining to any of the large organs of the ventral cavity, particularly those in the abdominal cavity.

You will recall from Module 4 that the suffix -eum means membrane. Periton/o is a combining form that refers to the peritoneum. The parietal peritoneum is that which lines the cavity; the visceral peritoneum covers the organs.

The peritoneum is a serous membrane, which means that it secretes serous fluid, a thin, watery liquid that lubricates the membrane, allowing smooth movement between the parietal and visceral peritoneum. An abnormal collection of serous fluid in the abdomen is called ascites.

You will recall from Module 3 that -centesis is a suffix that refers to a surgical puncture to remove fluid. Therefore, the surgical puncture of the abdominal wall to treat ascites is called abdominocentesis or abdominal paracentesis.

3.7 Abdominopelvic Cavity (animation)

The pelvic cavity is the area below the abdomen that contains the urinary bladder, the reproductive organs, part of the intestines, and the rectum.

Pelvic means pertaining to the pelvis. The term pelvis refers both to the lowest portion of the trunk of the body and to the innominate bones, the pair of hip bones that form the bony structure of the lower trunk.

Because the pelvic cavity is not separated from the abdomen by a dividing structure, these spaces are often jointly referred to as the abdominopelvic cavity.

3.9 Division of the Abdominopelvic Area

To continue our discussion of the body's orientation and organization, let's focus on the abdominopelvic area. It may be divided into nine regions by imposing four imaginary lines in a tic-tac-toe pattern over its anterior surface. These anatomical divisions help health care providers locate internal organs and serve as useful points of reference for describing health problems.

3.10 Abdominopelvic Regions

The imaginary lines that divide the abdominopelvic area form three upper, three middle, and three lower regions. The upper right and left sections are the hypochondriac regions; these are separated by the epigastric region, so named because it lies directly above the stomach.

The middle right and left sections are the lumbar regions, between which lies the umbilical region where the navel, or umbilicus, is located.

The lower right and left sections are called the iliac regions, because of their proximity to the ilium, the upper portion of the hip bone. These regions are also sometimes referred to as the right and left inguinal regions because they are near the groin and inguinal means pertaining to the groin.

The hypogastric region is the lower middle section below the umbilicus. You will recognize that this term means below the stomach.

The term umbilicus is from the Latin word umbo, which referred to the boss or protruding part of a shield. The term later came to signify a raised or depressed spot in the center of any object.

3.11 Umbilicus

As indicated earlier in this lesson, one combining form that indicates the umbilicus or navel is umbilic/o, and umbilical means pertaining to the navel, as illustrated by the umbilical hernia.

Another combining form with the same meaning is omphal/o. Omphalus means navel and omphalic is a synonym for umbilical. Omphalitis means inflammation of the umbilicus, and an omphaloma is a tumor of the umbilicus. Omphalorrhexis is the term for rupture of the umbilicus.

You will recall from Module 4 that omphalocele is a term that means umbilical hernia. The term for surgical repair of a hernia is hernioplasty.

3.12 Upper Abdominopelvic Quadrants (RUQ, LUQ)

The abdominopelvic area can also be divided into quadrants, four sections, by drawing imaginary vertical and horizontal lines through the umbilicus.

The right upper quadrant (RUQ) contains the right lobe of the liver, the gallbladder, part of the pancreas, portions of the small and large intestines, and the right kidney.

In the left upper quadrant (LUQ), we find the left lobe of the liver, the stomach, the spleen, part of the pancreas, portions of the large and small intestines, and the left kidney.

3.13 Lower Abdominopelvic Quadrants (RLQ, LLQ)

The right lower quadrant (RLQ) of the abdominopelvic region contains parts of the small and large intestines, the appendix, the right ureter, the right fallopian tube and ovary in women, and the right spermatic duct in men.

Located in the left lower quadrant (LLQ) are portions of the intestinal tract, the left ureter, the left fallopian tube and ovary in women, and the left spermatic duct in men.

3.14 Threaded Case Study: Karen

Karen has mentioned to Dr. Likens that, in conjunction with her new exercise program, she intends to introduce some changes in her diet, for example, the inclusion of more fruits and vegetables for dietary fiber. Consequently, Dr. Likens will ask about Karen's current and past nutritional habits, examine the abdominopelvic area, and explore any reported digestive problems.

4.1 Acromegaly

The body's paired appendages, the four limbs, are often referred to as the extremities. The arms with their component parts—the wrists, hands, and fingers—are the upper extremities; the legs—including the knees and feet—are the lower extremities.

The combining form acr/o denotes a relationship to an extremity. An example of its use in a medical term can be seen by adding the suffix -megaly, which means enlargement. The word acromegaly is defined as enlargement of the distal portions of the skeleton, a condition caused by excessive secretion of growth hormone in adulthood and marked by enlargement and thickening of the bones of the face and jaw (as seen in the illustration).

4.2 acr/o

The combining form acr/o is used in many medical terms that indicate conditions of the extremities.

You will recall that -osis is a suffix meaning condition and that cyan/o is the combining form for the color blue. Therefore, acrocyanosis is a condition in which the extremities appear blue. This persistent, uneven, bluish discoloration is also known as Reynaud's sign.

Acroparalysis is a term that means loss of motor function or sensation or both with respect to the extremities.

4.3 dactyl/o

Now let's look at some more word parts that are used to refer to the extremities.

The term digit refers to a finger or toe. The bones of the digits are called phalanges (sing., phalanx).

Dactyl/o is a combining form that means digit. When used in a medical term, dactyl/o may refer to either a finger or a toe. If we add the suffix -itis, which means inflammation, we form the word dactylitis, a painful inflammation of the fingers or toes (as seen in the illustration).

Dactylography is the analysis of fingerprints for identification, and the term for fingerprint is dactylogram.

Another term based on the combining form dactyl/o is dactylospasm, which refers to the muscle contraction of the fingers known as "writer's cramp."

4.4 chir/o, pod/o

In Module 3, you were introduced to the combining form chir/o, which means hand.

Pod/o, as you'll recall from Module 4, is a combining form that means foot. A chiropodist, now more commonly known as a podiatrist, is one who specializes in treating disorders of the foot.

The term chiropodist probably referred originally to those who manually—that is, by using their hands—treated pathologic foot conditions.

4.5 Somatogenic Classification for Disease Origins

Now we'll consider some terms that relate to the body in a more general way.

Recall from Lesson 1 of this module that somat/o is a combining form that means body. Let's add suffixes to this word part to form some commonly used medical terms.

You will recall from Module 4 that -genic means produced by or originating in. If we join the suffix -genic to somat/o, we create somatogenic, a term that means originating in the body.

Somatic death refers to the death of the organism and is characterized by the discontinuation of cardiac activity and respiration that eventually leads to the death of all body cells. For approximately six minutes after somatic death—a period referred to as clinical death—a person whose vital organs have not been damaged may be revived. Achievements of modern biomedical technology have enabled physicians to artificially maintain critical functions for indefinite periods following somatic death.

4.6 Psychogenic Classifications for Disease Origins

While many diseases are somatogenic, there are two other common classifications for disease origins. Exogenous diseases are the result of causes originating outside the body. Recall from Module 4 that psych/o means mind. Psychic means mental or pertaining to the mind, and psychogenic conditions are those that originate in the mind or are caused by mental processes.

Psychosomatic, therefore, means pertaining to the relationship and interaction between the mind and body and refers to the manifestation of bodily symptoms due to mental or emotional causes. For example, the role of mental and emotional stress is commonly recognized as a contributing cause of certain physical conditions including ulcers, asthma, and certain skin conditions. Psychophysiologic has the same meaning as psychosomatic but is less commonly used.

Somatopsychic, on the other hand, refers to the effects of the body on the mind. Diseases of the circulatory system, for example, may affect the blood supply to the brain, causing memory loss or other mental problems.

If you remember from Module 4 that esthesi/o is the combining form that means feeling, you will recognize that somesthetic means pertaining to the general feeling or sense of one's body and of the functioning of one's own organs. The somesthetic area of the brain is the part where the awareness of sensations occurs.

4.7 Conditions of the Head

Let's look at two more word parts that may be used to describe the body or body parts generally.

The prefixes macro- and micro- refer to size. Remember the combining form cephal/o, which, as we learned in an earlier lesson, means head? If we join the prefix macro- to the combining form cephal/o and add the suffix -ic, we construct the term macrocephalic, defined as pertaining to a large head.

Substituting the prefix micro- for macro-, we can build the terms microcephalus, which means abnormally small head, and microcephalic, meaning pertaining to microcephalus.

4.8 Conditions of the Brain

In previous modules, you encountered the combining form encephal/o, meaning brain. Any abnormal condition of the brain may be referred to as encephalopathy. If the condition involves inflammation, it is more likely to be termed encephalitis.

Recall that a machine to record the electrical activity of the brain is called an electroencephalograph, abbreviated EEG. Electroencephalography is sometimes used to determine whether there is brain function following the somatic death of an individual who is being maintained on artificial life support. When this test confirms a lack of brain activity, the individual may be said to be brain dead. Brain death is the cessation and irreversibility of all brain function, including the brain stem.

4.9 Development

In Module 4, you learned that the suffix -plasia means development. The following terms that use this suffix are applicable to the development of almost any part of the body.

Aplasia contains the prefix a-, meaning without, to form this term that means without development; it refers to the failure of development that results in the absence of an organ or tissue. Anotia, congenital absence of the external ear, is an example of aplasia. Dysplasia means abnormal development.

The prefix ana- may mean up, apart, or backward. In the term anaplasia, ana- means backward. Anaplasia is a change in the degree of differentiation of cells into a more primitive form, which is characteristic of malignancy.

Hypoplasia and hyperplasia refer, respectively, to underdevelopment and overdevelopment. Both of these terms refer to abnormal size of a structure related to the number of cells in the tissue or organ; that is, hypoplasia indicates an abnormally diminished number of cells, while hyperplasia is an abnormal increase in the number of cells.

When the size of a tissue or organ is abnormally increased due to enlargement of the cells, rather than an increase in their number, this condition is called hypertrophy, which literally means excessive nutrition. Although they have distinctly different meanings, the terms hyperplasia and hypertrophy are often used interchangeably.

4.10 Conditions of the Skin

You will recall that dermat/o and derm/o are combining forms that mean skin. The entire outer surface of the body is covered with skin. The abbreviation for body surface area is BSA.

If we join the combining form dermat/o with the suffix -osis, meaning condition, we form the term dermatosis, which refers to any disease of the skin, particularly one not involving inflammation.

If the skin condition involves inflammation, it is more properly called dermatitis because -itis is the suffix that means inflammation.

By combining this term with acr/o, we form acrodermatitis, which is inflammation of the skin of the extremities.

The term for skin graft is dermatoplasty, which literally means procedure to repair the skin.

5.1 Observation Process

In this lesson, we will learn about the essential parts of a physical examination, abbreviated PE, and some of the general types of conditions that are considered during the process of the physical exam.

At the beginning of the examination, the physician observes the patient while asking questions about the patient's current complaint or concerns, health history, social history, and family history.

In the observation process the physician notes the patient's general appearance, body shape, and degree of mobility, or ability to move about. If the physician notes that the patient is ambulatory, this means that he or she is capable of ambulation, or walking.

The physician will note the patient's skin color. A rosy or ruddy complexion may indicate an endocrine problem. A bluish coloration, which you will recall is called cyanosis, suggests cardiovascular problems. Perspiration, difficulty breathing, mental confusion, and general affect, or demeanor, are all important considerations that are included in the physician's initial evaluation by means of observation.

5.2 Inspection

The physical examination process consists of four specific examination methods: inspection, palpation, percussion, and auscultation.

Inspection is also a form of observation but is more specific than the general observation described in the previous screen. Inspection involves the careful visual examination of any areas of concern.

During the process of inspection, the physician will be alert for the appearance of any lesion. This term refers to any traumatic or pathologic change in tissue in a localized area. Most commonly this term indicates a visible abnormality of skin tissue, such as a wound, boil, rash, or sore.

Instruments may be used to enhance the physician's ability to inspect specific areas; for example, you will recall from Module 4 that an ophthalmoscope is an instrument used to inspect the eyes. Combining ot/o, meaning ear, and -scope, which denotes an instrument for viewing, the term otoscope refers to the instrument used to inspect the ears.

5.3 Palpation

In addition to inspection, the physician will palpate, or feel, specific areas of the body to obtain additional information. Palpation is the physical examination technique in which the examiner applies light pressure with the fingers to the surface of the body for the purpose of feeling the size, texture, consistency, and location of certain body parts.

The examination of Karen's abdomen, illustrated here and in Lesson 3 of this module, is an example of palpation.

5.4 Percussion

Another important examination technique is percussion, in which the examiner taps a body part with short, sharp blows and listens to the sounds obtained so as to determine the size, borders, and consistency of underlying parts. Percussion is particularly helpful in evaluating the chest and the abdomen.

5.5 Auscultation

The fourth, and final, examination method is auscultation, the act of listening to sounds within the body for the purpose of evaluating the condition of the lungs, heart, blood vessels, pleura, abdomen, or other organs.

The stethoscope is the instrument used to perform auscultation. It consists of two earpieces connected by flexible tubing to a diaphragm that is placed against the surface of the skin. It amplifies sounds within the body so that they can be heard and identified. Note that although this term contains the suffix -scope, it refers to an instrument for listening, not for viewing.

5.6 Vital Signs

In addition to the examination methods we have discussed so far, the physical examination includes four assessments of body processes known as vital signs. The abbreviation for vital signs is VS or vs. The vital signs include the measurement of body temperature, pulse rate, respiratory rate, and blood pressure. These assessments are discussed further in other modules.

6.1 Drug Classifications: Antiinflammatories

In Module 2, you began to learn some of the terminology that describes the properties, uses, and actions of drugs. We saw how drugs are organized into classes based on their effects and we considered some examples within those categories. Now, we'll learn about a few more drug classes, focusing on their effects and uses.

You will recall from Module 4 that inflammation is the body's response to disease and injury. The classic signs of inflammation are redness, swelling, warmth, and pain. The term inflammatory means pertaining to or characterized by inflammation.

The antiinflammatory drugs, as the name suggests, are used to counteract or reduce inflammation.

6.2 Drug Classifications: Antipyretics

In Module 4, you learned that the combining form pyr/o means fire and the related combining form, pyrex/o, means fever, an abnormally high body temperature. Terms that mean fever include pyrexia, the condition of fever, and hyperthermia, excessive heat.

A term that means pertaining to a fever is febrile. A substance or agent that tends to produce fever is usually referred to as a pyrogen but may also be called a pyretogen, a pyretic, or a pyrectic.

When prefixes are added, these terms take on new meanings. For example, afebrile means without fever.

The terms antifebrile and antipyretic refer to agents that reduce or alleviate fever.

Many of the antiinflammatory drugs also have an antipyretic effect; that is, they are capable of reducing fever. Readily recognized drugs within these categories are aspirin, ibuprofen, and acetaminophen.

6.3 Drug Classifications: Antiinfectives

The class of antiinfectives includes all drugs that are used to fight infections. This class contains many subgroups, all of which work to kill or inhibit the growth of disease-causing organisms.

The terms that indicate these organisms include microorganism and microbe, living entities too small to be seen without a microscope, such as bacteria, viruses, fungi, and protozoa. A microorganism capable of causing disease may be referred to as a pathogen.

Various antiinfectives act against a variety of bacteria, viruses, parasitic worms, and other pathogens. They are often referred to as antibiotics because the combining form for life is bi/o, and these drugs act against living organisms.

The penicillins are an important and widely used antibacterial subgroup of antiinfectives that are usually made from other living cells but can also be produced synthetically. The penicillin drugs, examples of which include Amoxicillin, Ampicillin, and Tetracycline, are prescribed to treat infections caused by bacteria.

Module 7

Introduction

In this module, you will learn about word parts and terms that are related to the blood and other fluids of the body. You will understand how these fluids, and the cells they contain, work to respond to injury and disease.

Exercises in this module may require you to review the structure of medical terms introduced in Module 1.

Remember that this integrated learning program is intended as a supplement to your text—not as a substitute. Be sure to keep your text available for ready reference.

Objectives

In this module, you will learn to:

• Recognize general facts about body fluids.
• Recognize the meaning of word parts pertaining to body fluids and immunity and use them to write terms.
• Identify the functions and principal conditions that affect erythrocytes, leukocytes, and blood platelets.
• List several body defense mechanisms.
• List four general types of microorganisms.
• Recognize the four classifications of bacteria.
• Define active versus passive immunity and natural versus artificial immunity.
• Name several nonspecific body defense mechanisms and describe the two aspects of specific immune response.

Section I: Blood and Other Body Fluids

1.1 Water

We begin our discussion of body fluids with water, the most prevalent fluid of the body. It makes up a significant part of most body fluids and constitutes more than half of the body's total weight.

The combining form that means water is hydr/o. Hydration refers to the absorption of water. When the body is adequately hydrated, the tissues have a sufficient supply of water. Dehydration, on the other hand, refers to excessive loss of water from the body, resulting in an insufficient supply of fluid to the tissues.

The body strives to maintain a constant internal environment. This process is called homeostasis. This term comes from the combining form home/o, meaning constancy or sameness, and -stasis, which means control. Regulation of the amount of water in the body is called fluid balance. Maintaining the fluid balance is an important aspect of homeostasis.

1.2 Cells

In Module 4, you learned that cyt/o and -cyte mean cell. The combining form cellul/o has a similar meaning, denoting little cell or compartment. It is the basis of the term cellular, meaning pertaining to a cell.

Module 5 introduced the prefixes intra- and extra-, meaning within and without, respectively. Therefore, intracellular means within the cell, and extracellular means occurring or situated outside a cell or cells.

More than half of the body fluid is intracellular, contained within the cells. There are two types of extracellular fluid: plasma, which is the liquid portion of blood and is contained within the blood vessels, and interstitial fluid, a clear liquid resembling plasma that fills the spaces between most body cells and constitutes a large portion of the liquid environment of the body. Oxygen and nutrients dissolved in blood pass through the walls of the blood vessels and become part of the interstitial fluid that surrounds and bathes the cells. The oxygen and nutrients are then absorbed through the cell walls for utilization within the cells.

Another way of classifying body fluids is to differentiate between those that are secreted and those that are excreted. Secretion is the process of discharging a substance into a body cavity or organ. For example, gastric juices are secreted into the stomach. Excretion refers to the process of eliminating substances from the body. Urine is an example of a body fluid that is excreted.

1.4 Body Fluids

Many different fluids are associated with the various body systems. They include cerebrospinal fluid, urine, mucus, perspiration, and gastric juices, in addition to lymph and blood.

As this lesson continues, we will consider these fluids and how they are related to the systems with which they are associated.

Laboratory tests analyze and measure the constituents of various body fluids and are used to evaluate organ function, diagnose diseases, and manage treatment.

1.5 Blood

When body fluid is mentioned, the first liquid that is likely to come to mind is blood. Blood is a complex fluid that is pumped by the heart through the arteries, veins, and capillaries. Its principal function is to maintain a constant environment for the other living tissues of the body. It transports nutrients and oxygen to the cells and carries carbon dioxide and wastes from the cells for elimination from the body.

Recall from Modules 2 and 3 that hem/a, hem/o, and hemat/o are combining forms that mean blood. Hematology is the term for the study of blood or the medical specialty that treats diseases of the blood. A hematologist is a physician specializing in hematology, and hematologic means pertaining to hematology.

You may be familiar with the term sanguine, which in conversational English means optimistic or cheerful. In medical terminology this term means pertaining to blood. Sanguinous means containing blood. There are a number of additional terms that are based on sanguis, that Latin word for blood, but most are not commonly used.

1.6 Threaded Case Study: Li Chen

As we learn about the blood, we'll follow the case of Li Chen. During a complete physical exam, Li mentions to his doctor that he seems to catch colds more easily and often feels fatigued. He also says he has lost some weight. Hearing this, the physician decides to order some laboratory tests for blood analysis.

1.7 Cardiovascular System

The heart and the blood vessels make up the cardiovascular system. Note that this term is built from parts that are familiar; it combines cardi/o, meaning heart, vascul/o, meaning vessel, and -ar, meaning pertaining to. Blood is an intravascular fluid, meaning that its normal location is within the blood vessels.

1.8 Plasma

Blood is a connective tissue composed of a clear, straw-colored fluid called plasma and formed elements, or blood cells, which are suspended in this plasma.

The plasma consists primarily of water, but it also contains proteins, sugar, salts, hormones, and vitamins. It picks up waste liquids and gases and transports them to the kidneys and the lungs for elimination from the body. Plasma accounts for 55% of the blood's total volume.

1.9 Formed Elements

There are three basic types of formed elements, or blood cells: red blood cells (RBCs), called erythrocytes; white blood cells (WBCs), known as leukocytes; and thrombocytes, also called platelets, which are cell fragments that initiate the formation of a clot.

These terms for blood cells should be easy to remember because you are already familiar with their component parts. Recall that leuk/o means white, erythr/o means red, and thromb/o means clot.

You will learn more about the constituents of blood from later lessons in this module.

1.11 Electrolytes

The essential salts that are part of the blood and other body fluids include electrolytes, molecules that conduct electricity. Some important electrolytes found in body fluids are salts that contain calcium, potassium, and sodium. An imbalance of electrolytes may cause serious abnormal conditions, and certain diseases may cause such an imbalance.

The combining form for calcium is calc/i and the suffix -emia denotes a relationship to a blood condition. Thus, a deficiency of calcium in the blood is termed hypocalcemia.

Potassium is indicated by the combining form kal/i. A deficiency of potassium in the blood would be signified by the term hypokalemia.

Natr/o is the combining form that denotes a relationship to sodium. Thus, hyponatremia is the term that means deficiency of sodium in the blood.

Remember that hyper- is the prefix that indicates an excessive amount. What are the terms for excessive amounts of calcium, potassium and sodium in the blood?

Congratulations if you knew that hypercalcemia, hyperkalemia, and hypernatremia were the terms for excessive amounts of calcium, potassium, and sodium, respectively, in the blood.

1.12 Lymph

The lymphatic system is a network of lymph nodes, lymph vessels, and organs that have several important functions: to maintain the fluid balance by absorbing excess fluid from the spaces surrounding the cells, to absorb fats from the small intestine, and to play a vital role in the immune system. The clear, watery fluid that flows within the lymphatic system is called lymph.

Lymph is similar to interstitial fluid, but it also contains leukocytes and proteins that are active in the process of providing immunity, protection from disease. Immun/o is the combining form that means immunity.

The combining form that means lymph is lymph/o. The term lymphatic means pertaining to lymph or lymph vessels.

You will recall from Module 3 that one of the combining forms that means vessel is angi/o; therefore, the combining form that means lymph vessel is lymphangi/o. Lymphangitis means inflammation of one or more lymph vessels. A lymphangioma is a benign tumor consisting of a mass of dilated lymph vessels; it represents a congenital malformation of the lymphatic system.

1.13 Sweat

The integumentary system consists of the skin and the auxiliary organs of the skin, including the sweat glands and the sebaceous (oil) glands. The combining form for sweat is hidr/o. Take care not to confuse this word part with hydr/o, meaning water.

Perspiration is a synonym for sweat. Hidrosis refers to the condition of perspiring or sweating. Another term that means hidrosis is diaphoresis.

Perspiration contains water, salts, and waste products. One important function of the sweat glands is to rid the body of these wastes by secreting sweat. The other important function is to maintain homeostasis and body temperature by cooling the body when it becomes overheated. The evaporation of sweat from the skin lowers the body temperature.

The combining form meaning sweat gland is hidraden/o—a combination of hidr/o, meaning sweat, and aden/o, meaning gland. Thus, hidradenitis is a term that means inflammation of a sweat gland (see illustration), and a hidradenoma is a benign tumor of a sweat gland.

1.14 Cerebrospinal Fluid

The dorsal cavity of the body contains cerebrospinal fluid, a clear, watery liquid that surrounds the brain and the spinal cord and fills the ventricles of the brain. The abbreviation for cerebrospinal fluid is CSF.

You will recall from Module 4 that cephal/o is the combining form for head. Earlier in this lesson you learned that hydr/o means water. Therefore, hydrocephalus is a term that literally means water in the head. It is the name of a condition characterized by dilation of the cerebral ventricles and accumulation of cerebrospinal fluid within the skull. Hydrocephalus is also called hydrocephaly.

In hydrocephalus, the ventricles of the brain become enlarged with CSF. This condition causes the brain tissue to become compressed against the skull, causing serious neurological problems.

The goal of treatment for hydrocephalus is to reduce or prevent brain damage by improving the flow of CSF. Surgical removal of the obstruction is desirable but not always possible. If the obstruction cannot be removed, a shunt, or small tube, may be placed within the brain to allow the fluid to bypass the obstructed area.

Redirecting the CSF to an area outside the brain, such as the right atrium of the heart or the peritoneal cavity, is an alternative to shunting within the brain.

1.16 Mucus

Another body fluid of interest is mucus. Mucus is the slippery secretion produced by the mucous membranes that line body cavities such as the mouth, nose, and digestive tract. This substance lubricates body linings and protects them from injury, infection, and dehydration.

Mucus is composed of water, mucin, salts, leukocytes, and cells shed by the mucous membranes. Mucin is a glycoprotein, a chemical combination of a sugar and a protein, giving mucus its slimy consistency. Mucin is also found in other body fluids and is a component of egg white.

The combining form muc/o means mucus. The related term mucous means pertaining to mucus. Note that there is a small difference in spelling, but the pronunciation of mucus and mucous is the same.

Mucoid means mucus-like or resembling mucus; the suffix -oid means like or resembling.

1.17 Saliva

Saliva is the clear liquid that is secreted into the mouth by the salivary glands. Saliva moistens the mouth, aids in swallowing, and contains an enzyme that initiates the digestion of starch.

The combining form that indicates saliva is sial/o. The combining form for salivary gland may be either sial/o or sialaden/o. For example, both sialitis and sialadenitis are terms that refer to inflammation of one or more salivary glands.

Recall that -lith is a suffix meaning stone or calcification. A sialolith, then, is a calculus or concretion in a salivary gland or a salivary duct. Sialography is the procedure of making radiographic images of the salivary glands and ducts, often for the detection of a sialolith.

1.18 Urine

Urine is the body fluid excreted by the kidneys. Normal urine is amber-colored and slightly acidic, with the characteristic odor of urea.

After it is formed in the kidneys, the urine flows through the ureters to the bladder where it is stored until it is expelled from the body through the urethra. Thus, the kidneys, ureters, bladder, and urethra make up the organ system known as the urinary tract. Both ur/o and urin/o denote a relationship to urine or to the urinary tract. Nephr/o and ren/o are combining forms that refer specifically to the kidney.

The medical specialty that treats conditions of the urinary tract is urology. Urinalysis is the term for the laboratory examination of urine to aid in diagnosis.

As you were reminded in a previous screen, -lith is the suffix that means stone or calculus. Calcifications in the urinary tract are a common condition known as kidney stones in lay terms and as nephrolithiasis in medical language. In Module 3, you learned about lithotripsy, a noninvasive treatment for nephrolithiasis. Another treatment is nephrolithotomy, meaning removal of one or more kidney stones through a surgical incision. The name of this procedure is often shortened to lithotomy. While lithotomy is the term for an incision to remove any stone, the term is most often applied to the removal of stones from the urinary tract.

Lithotomy was originally performed with the patient in the lithotomy position, one in which the patient lies on the back with the hips and knees flexed and the thighs rotated outward. The same position is more commonly used now for obstetrical and gynecological procedures.

1.19 Pus

The body fluids discussed up to this point are found in all healthy individuals. Pus is the liquid product of infection and is found only in diseased tissue, as the illustration of pustular psoriasis demonstrates. Pus contains water, proteins, bacteria, and leukocytes; it is usually yellow in color and somewhat thick in consistency.

The combining forms py/o and purul/o mean pus. Pyogenic means producing or forming pus. Pyothorax is a term that means pus in the thoracic cavity.

The terms suppurative and purulent mean characterized by pus and are used to describe the discharge from infected wounds. A discharge described as sanguinopurulent contains both blood and pus.

A localized collection of pus in a cavity surrounded by inflamed tissue is called an abscess. The presence of an abscess promotes the infectious process. If it is not treated, the surrounding tissue may disintegrate and die.

The combining form that means death is necr/o; necrosis refers to the condition of localized tissue death. Tissue that undergoes necrosis is referred to as necrotic.

2.1 Development of Blood Cells

Two terms that refer to blood cells are hemocyte and corpuscle. Most blood cells originate in the bone marrow through a process called hematopoiesis. The suffix -poiesis means formation.

The immature cells, called hemocytoblasts or hematopoietic stem cells, are pluripotent; this term literally means many possibilities and indicates that these cells can develop into several different mature cell types, usually in response to hormonal influences. The mature cells function in specialized ways. The process of developing from a stem cell to a mature, specialized cell is called differentiation.

In some blood diseases, particularly those that involve an excessive number of certain cells, large numbers of immature cells will be prematurely sent into the blood stream. Their identification in blood samples is useful in diagnosis. The suffix that means immature and indicates an immature cell is -blast. Note the cells in this diagram whose names have this suffix. They are immature precursors to the cells found in the blood stream.

2.2 Red Blood Cells

You will recall from the previous lesson that the formed elements, or cells, contained in blood are of three basic types: red cells, white cells, and platelets. First we will consider the red blood cells.

Red blood cells (RBCs) are also called erythrocytes. They are the most numerous of all the formed elements, averaging 4 to 6 million per cubic millimeter. RBCs are tiny pliable disks that are concave on both sides; they perform the critical task of carrying oxygen from the lungs to the cells and help to maintain the proper pH of the blood and tissues by removing carbon dioxide, a gas that is a waste product of cell metabolism, carrying it back to the lungs where it is exhaled from the body.

The combining form erythr/o means red and the suffix -poiesis means production. Therefore, red blood cell production is called erythropoiesis. Erythropoietic means pertaining to the production of red blood cells.

Erythrocytes are produced in response to the kidney's secretion of the hormone erythropoietin (EPO).

The biconcave shape of a red blood cell gives it a large surface area relative to its volume. In fact, in an adult, the total surface area of all red blood cells is larger than a football field.

2.3 Hemoglobin

Once an erythrocyte matures, it has no nucleus, nor does it have many of the other structures typically found in body cells. Instead, packed into each red blood cell are hundreds of molecules of hemoglobin. Hemoglobin consists of heme—the pigmented, iron-containing portion of the molecule—and globin, a protein chain. The transport of oxygen and carbon dioxide to and from the lungs relies on the ability of hemoglobin to combine with these gases. Hemoglobin gives blood its red color.

2.4 Complete Blood Count

There are many types of blood tests, some of which will be explained later in this module. A group of tests commonly used for screening purposes and in the general evaluation of a patient's physical condition is the complete blood count, abbreviated CBC. These tests involve counting the numbers of various types of cells in a specific volume of blood or in a field on a microscopic slide, plus the measurement of various components of blood. The tests included in a CBC will be identified as you learn about the factors they measure.

This illustration shows a Neubauer counting chamber, a special type of microscope slide used to count the number of cells in a sample of biological fluid. In this example, the chamber is being used to count erythrocytes. The red blood cell count is one of the tests that is a component of a CBC. The red cell count is a precise estimate of the number of erythrocytes per microliter (mcl) of blood based on the number of cells in a tiny sample. The normal RBC count is 4.7 to 6.1 million cells/mcl for males and somewhat fewer, 4.2 to 5.4 million cells/mcl, for females.

Another aspect of the CBC that evaluates the erythrocyte component of blood is the measurement of hemoglobin, the protein that carries oxygen and carbon dioxide in the blood. Hemoglobin is abbreviated Hb or Hgb. The hemoglobin test measures the number of grams of this blood protein in one deciliter (dl, 100 milliliters) of blood. The normal hemoglobin values are 14-18 gm/dl for adult males and 12-16 gm/dl for females.

A third portion of the CBC that evaluates the erythrocyte component of blood is the hematocrit, abbreviated HCT or Hct. Hematocrit is a measurement of the percentage of blood that consists of red cells. This test is accurately described as the packed red cell volume and is sometimes called "packed cell volume" or PCV. The normal range of hematocrit is between 41 and 50% in adult males and between 36 and 44% in females.

Although these tests may be done individually in the laboratory by a qualified technologist, automated machines can perform a number of blood tests quickly and accurately and are commonly used to analyze blood samples.

2.5 Threaded Case Study: Li Chen

At his doctor's recommendation, Li has been to the lab to have his blood tested. Thus far, results of Li's blood tests show a lower than normal number of red blood cells.

2.6 Destruction of RBCs

Red blood cells live for about 120 days and then are destroyed by special cells called macrophages, which are found in the liver and spleen. Macrophages break the red blood cells into their component parts of heme and protein. Heme is broken apart into iron and the pigment bilirubin.

The combining form hem/o means blood and the suffix -lysis means destruction. Thus, the term hemolysis literally means destruction of blood but is used specifically to apply to the breaking down of erythrocytes.

Globin, the protein portion of the hemoglobin molecule, converts to amino acids. The iron may either be stored in the liver or returned to the bone marrow to produce new hemoglobin. Bilirubin is transported to the liver to be excreted into the small intestine as a component of bile. The amino acids are used to form new proteins.

2.8 White Blood Cells

White blood cells (WBCs) are also called leukocytes. They are much less numerous than red blood cells. They differ greatly from RBCs in that they are much larger and have nuclei. WBCs participate in the process of protecting the body from infection.

Five types of mature white cells are found in normal blood. Three of these types have granules (small grains) in their cytoplasm and are therefore categorized as granulocytes. The granulocytes are named according to the color of their granules as seen on a stained blood smear treated with two types of dye. Acidic dye stains the granules a pinkish color and nonacidic or basic dye stains them a deep blue-violet color.

The other two types of leukocytes have no granules. Using the prefix a-, meaning without, these cells are called agranulocytes.

2.9 Neutrophils

Let's first consider the granulocytes.

The suffix -phil means attraction for, so the granulocytes have names that end with this suffix, indicating the color of dye that stains them.

About 65% of the leukocytes in a normal blood sample are neutrophils. These cells have granules that do not stain intensely with either dye and therefore appear a sort of gray-lavender color, a neutral shade that is neither pink nor deep blue-violet.

Neutrophils are the body's primary defense against bacterial infection. They are the first type of white blood cell to arrive at the scene of injury, where they engulf and destroy harmful microorganisms over their life span of 6 to 24 hours.

2.10 Granulocytes

Granulocytes are formed in red bone marrow, or myeloid tissue. Their production, maturation, and activation are triggered by special proteins called colony-stimulating factors (CSFs).

You will recall that the prefix poly- means many. The combining form morph/o means shape, and nucle/o indicates a relationship to the nucleus. As granulocytes mature, they develop multilobed nuclei, making them polymorphonuclear.

Consequently, these cells—particularly neutrophils—are sometimes called polymorphonuclear (PMN) leukocytes, or polymorphs.

2.11 Basophils

In addition to neutrophils, the other two types of granulocytes are basophils and eosinophils.

The combining form bas/o refers to a base or alkali, the opposite of an acid. Basophils are so named because their granules stain a dark blue-violet color when treated with a dye that is a base.

Basophils are the smallest circulating granulocytes with relatively the least known function. They arise in the bone marrow, and following maturation and differentiation, are released into the blood circulation. When stimulated, basophils release histamine, serotonin, and heparin, substances that affect the reparative processes involved in inflammation.

2.12 Eosinophils

The third type of granulocyte is the eosinophil. It is characterized by large red or bright pink granules in its cytoplasm. The combining form eosin/o means red or rosy and comes from Eos, the Greek goddess of dawn.

Eosinophils are produced in the bone marrow and migrate to tissues throughout the body. Their function is not completely understood. They are prominent at sites of allergic reactions and with infections by parasitic larvae. They secrete products that inactivate many of the chemical mediators of inflammation, and they also destroy cancer cells.

When a foreign substance enters the body, other lymphocytes release certain substances to attract eosinophils; the eosinophils then release toxic substances to kill the invader.

2.13 Lymphocytes

There are two types of agranulocytes: lymphocytes and monocytes. They have singular, somewhat rounded nuclei.

Lymphocytes are small leukocytes that account for about 25% of all white blood cells. Although mature lymphocytes all look pretty much alike, they are extraordinarily diverse in their functions. The most abundant lymphocytes are B lymphocytes, also called B cells, and T lymphocytes, likewise called T cells.

Lymphocytes help mediate the body's immune response, either by attacking infectious agents directly or by producing antibodies. You will learn more about the functions of lymphocytes in subsequent lessons.

2.14 Monocytes

Monocytes are the largest of the leukocytes. Although classified as agranulocytes, monocytes actually contain many very fine granules, which appear both red and blue when stained.

Monocytes are active in the immune process, ingesting bacteria and tissue debris.

Monocytes can leave the circulation and enter the body's tissues, whereupon they become the special phagocytic cells known as macrophages. You encountered this term earlier in this lesson because these slow-moving but powerful cells are involved in the breakdown of old red blood cells. They also ingest bacteria, old or defective cells, tissue debris, and virus-infected cells.

2.15 Phagocytes

Phagocytosis is the ingestion and destruction of microorganisms, foreign material, and cellular debris within the tissues. As you may recall from Module 4, this term is applied to cells that are capable of engulfing and destroying particles by phagocytosis, as illustrated here. Phagocytes are among the first cells to arrive at the site of an injury. The primary phagocytic cells in the blood are the neutrophils and monocytes.

As you have just learned, monocytes become macrophages when they leave the blood and enter the tissues. Macrophages are phagocytes that are larger than monocytes and have a longer lifespan. They do not circulate in the blood.

2.16 Threaded Case Study: White Blood Cell Count

A complete blood count includes two tests that evaluate leukocytes: the white blood count and the white blood cell differential count.

The white blood count may be variously referred to as WBC count, leukocyte count, or white count. It is simply an enumeration of the total number of leukocytes in one microliter of blood. Normal values range between 4,500 and 10,000 and vary somewhat according to age and gender.

The white blood cell differential count may be referred to simply as the differential or "diff." It is a statement of the percentage of white blood cells represented by each of the five basic types of cells, plus any immature cells that may have been prematurely released from the bone marrow. These immature cells are usually called band cells but may also be referred to as "stabs." When the test is performed manually, the leukocytes in a stained blood smear on a microscope slide are counted until the total reaches one hundred; thus, the number of each cell type counted represents a percentage of the total. The sum of the percentages in a differential count equals 100%. Normal adult ranges are:

Neutrophils:	50-60%
Lymphocytes:	20-40%
Monocytes:	2-6%
Eosinophils:	1-4%
Basophils:	0.5-1%
Bands:	0-3%

The report on the white blood cell differential that was part of Li's complete blood count revealed that he has an increased number of polymorphonuclear (PMN) neutrophils and a normal number of both lymphocytes and monocytes.

2.18 Threaded Case Study: Li Chen

Some time has passed and Li Chen's blood tests have been repeated. His platelet count was high initially, but his latest count is lower. What could this mean? To answer that, we must first answer the question: What role do the platelets play in circulation?

2.19 Thrombocytes

In addition to red blood cells and white blood cells, the platelets, also called thrombocytes, make up a third formed element of the blood.

These small, irregular cells are formed when large cells within the bone marrow, called megakaryocytes, fragment. This term is built from the prefix mega-, meaning large, the combining form kary/o, which means nucleus, and the suffix -cyte, which of course means cell. Thus, a megakaryocyte is a cell with a large nucleus.

The platelet's primary function is to aid in blood clotting. You will recall that the combining form thromb/o means clot.

2.20 Plasma

Plasma, the liquid portion of the blood, performs a variety of vital functions. It carries the cellular elements of the blood through the circulation and transports nutrients and wastes to and from the body's tissues.

Plasma consists of roughly 90% water and 10% other substances, the majority of which are proteins.

Two plasma proteins, fibrinogen and prothrombin, are essential elements in the blood clotting process.

Another protein component of plasma is albumin, which helps to maintain the proper balance of water between the capillaries and the tissues. Failure to maintain this balance can result in the abnormal accumulation of fluid in the tissue spaces, a condition known as edema.

2.21 Coagulation

Injury to blood vessels sets in motion a complex process, the purpose of which is to prevent blood loss. Within seconds after damage occurs, platelets coagulate, that is, they collect and clump together, forming a platelet clot at the injury site and releasing the protein thromboplastin.

Thromboplastin initiates further coagulation, the clotting process, by converting the plasma protein prothrombin to thrombin in the presence of calcium. Thrombin then causes fibrinogen, another plasma protein, to change to fibrin. Fibrin, a threadlike substance, traps red blood cells to form a fibrin clot.

2.22 Serum

Serum is the clear, watery fluid portion of the blood that remains after a clot has formed. Serum is plasma minus the clotting proteins and cells.

2.23 Antigens and Antibodies

An antigen is a substance that has the capacity to induce a specific immune (protective) response and to react with the products of that response. Most antigens are foreign substances, like bacteria and viruses. When these foreign substances enter the body, special proteins called antibodies are produced to help the body cope with the invading antigen.

Some antigens, however, are molecules that exist normally in the body. In fact, some of these native antigens bind to the surfaces of red blood cells.

2.24 Blood Types

Blood is classified into types, or groups, based on the antigens on the red blood cell surfaces.

In Type A blood, A antigens are found on the erythrocyte membrane. Type B blood contains B antigens. Type AB has both antigen A and antigen B. Type O blood contains neither A nor B antigens.

Blood plasma may also contain antibodies that react against either A or B antigens. But plasma will not normally contain antibodies that react against the antigens found on its own red blood cells. Consequently, Type A blood contains anti-B antibodies only. Similarly, only anti-A antibodies will be found in Type B blood.

2.25 Transfusion

Sometimes blood must be administered to patients as part of disease management or to replace blood lost due to trauma or surgery.

In a procedure called transfusion, whole blood—cells and plasma—or blood components are introduced into a recipient's bloodstream.

Blood products are obtained by a process called apheresis, separation of blood components by spinning them at high speeds in a centrifuge.

Before blood is transfused, special testing must be done to ensure that no adverse antigen-antibody reaction occurs. If, for example, Type A blood is given to a Type B recipient, the mixture of antigens and antibodies will cause clumping, or agglutination, of the blood, which is potentially fatal.

The test for compatibility between a blood donor and a recipient is called a type and cross-match.

2.26 Threaded Case Study: Blood Compatibility

Li Chen has Type AB blood, and his wife Meng has Type O. Because Type AB has both antigens, it contains neither anti-A nor anti-B antibodies. Type O blood has both antibodies because it contains no antigens.

Because Type O blood contains neither antigen A nor B, it can be administered with minimal risk of agglutination. For this reason, Meng and other individuals with Type O blood are referred to as universal donors.

Persons with Type AB blood, like Li, are called universal recipients because their blood contains neither the anti-A nor anti-B antibodies. Consequently, they can safely receive blood from any donor type. So Li can receive blood from his wife if the occasion arises, but she cannot receive blood from him.

2.27 Rh Factor (slide show)

Rh factor is another type of antigen found on the erythrocyte surface in many people. Those whose blood contains this antigen are said to be Rh-positive; persons who lack the factor are Rh-negative.

Normally, anti-Rh antibodies are not present in the blood. However, if an Rh-negative person receives Rh-positive blood, antibodies will form. With a second exposure to Rh-positive blood, those antibodies will react against the antigen, causing the blood to clump.

Rh-positive red blood cells can enter the bloodstream of an Rh-negative person in two ways: during transfusion or during pregnancy. An Rh-negative mother who delivers an Rh-positive child will, if she remains untreated, develop antibodies against the Rh factor. This will cause a harmful antigen-antibody reaction in subsequent Rh-positive children.

Section II: Pathologic Conditions Involving Blood and Blood Cells

1.1 Hyperemia

Before we look at diseases affecting the blood cells, this short lesson will consider conditions involving blood where the blood itself is not necessarily abnormal. These conditions are usually associated with trauma or other disease processes.

Module 4 presented the suffix -emia, which indicates a condition of the blood. Hyperemia is a term that refers to the condition of an excessive amount of blood in a body part. Hyperemia often occurs as a result of inflammation, causing warmth and reddening in the affected area. The term sanguineous is similar in meaning to hyperemia; it means having an abundance of blood.

1.2 Hemorrhage

The term hemorrhage refers to bleeding, the escape of blood from one or more vessels; it is often used to denote specifically the loss of a large amount of blood in a short period of time, either externally or internally, as in the subconjunctival hemorrhage shown in the illustration. This hemorrhage is secondary to blunt ocular trauma.

You will recall that the combining form thorac/o means chest; when hemorrhage results in blood in the pleural cavity around the lung, this condition is called a hemothorax.

1.3 Hematoma

A hematoma is a localized collection of blood (usually clotted) in an organ, tissue, or space, caused by a break in the wall of a blood vessel. This term combines hemat/o, meaning blood, with -oma. You will recall that -oma can mean tumor or swelling; it can also refer to a collection of fluid.

Hematomas can occur almost anywhere in the body, but are most serious when they occur inside the skull, as seen in this postmortem photograph of a brain. A simple bruise is a familiar form of hematoma.

2.1 Blood Dyscrasias

In the preceding units, we've considered the normal formation, composition, and functions of blood. Now we'll look at blood dyscrasias, abnormal conditions of the blood and bone marrow, beginning with disorders of the red blood cells.

2.2 Threaded Case Study: Anemia

Remember that Li Chen's blood tests revealed an abnormally low number of erythrocytes. This condition is known as anemia. In Li Chen's case, this condition appears to be the result of low red blood cell production. Shortly, we will learn about a possible reason for this finding.

Another name for anemia is erythrocytopenia or erythropenia. The combining form erythr/o means red; cyt/o means cell; and -penia means decreased or deficient.

2.3 Iron Deficiency Anemia

Anemia is a reduction in the number of red blood cells and, consequently, in the amount of hemoglobin in the blood. The suffix -emia means blood condition, and the prefix a- or an- means not or without.

Anemia may be caused by diminished red blood cell production, blood loss, or increased destruction of red blood cells, which, you will recall from an earlier lesson in this module, is termed hemolysis.

The red blood cells of a person who is anemic often differ in their size, shape, and appearance from those of a healthy person. There are several different kinds of anemia; we'll explore just a few here.

One example is iron-deficiency anemia, one of the most common blood disorders. In this condition, there is an insufficient amount of the iron needed to synthesize hemoglobin. You'll remember that the heme in hemoglobin gives blood its red color. The erythrocytes of a person with iron-deficiency anemia are microcytic, smaller than normal, and hypochromic, lacking in color. The combining form chrom/o means color.

Iron deficiency may develop from inadequate intake, poor absorption of iron, blood loss, or red blood cell destruction. Treatment of this condition involves the use of iron supplements and attention to the underlying cause of reduced intake or malabsorption.

2.4 Microcytes and Macrocytes

You will recall from Module 5 that the prefix micro- means small and that macro- means large.

Another characteristic of iron deficiency anemia, and sometimes other types of anemia as well, is that the erythrocytes tend to be microcytic, smaller than normal. Microcyte simply means small cell, but this term is applied almost exclusively to red blood cells.

Conversely, abnormally large red cells are referred to as macrocytes.

The combining form is/o means same or equal. You will recall that the prefixes a- and an- mean not. Therefore anisocytosis means the condition in which the cells are not of equal size. This term applies particularly to erythrocytes. Anisocytosis is common in cases of anemia.

When erythrocytes appear to be normal in size, they are called normocytes, or the cells are described as normocytic. The combining form norm/o means related to rule or order and is the basis for the common term normal.

2.5 Aplastic Anemia

Aplastic anemia is characterized by deficient red blood cell development. This term is a combination of a-, meaning no, and -plastic, meaning formation or development.

In fact, this failure of the cell-generating ability of the bone marrow results in a deficiency of all of the cellular elements of the blood—a condition known as pancytopenia. You will recall that pan- means all, so this term literally means deficiency of all cells, but actually means an insufficient number of all types of blood cells.

Aplastic anemia is sometimes congenital, but it may also be caused by exposure to radiation, chemicals, or certain infectious agents. It can also result from the use of certain medications.

The red coloration of these bones is due to the hemoglobin of the red blood cells within the marrow. From top to bottom, the bones are a tibia (lower leg bone), femur (thigh bone), rib, and spine. The bones have been split to reveal the marrow.

2.6 Hemolytic Anemia

Hemolytic anemia occurs when red blood cells are destroyed at a rate faster than the bone marrow can replace them. You have learned that lys/o means destruction. Thus, hemolytic means pertaining to blood destruction and refers specifically to erythrocytes. This type of anemia may be congenital or acquired.

Acquired hemolytic anemia is sometimes caused by an autoimmune disorder in which antibodies develop and attack antigens on the red blood cell membrane. The rapid destruction of erythrocytes in hemolytic anemia elevates the amount of bilirubin in the blood, which causes jaundice, a yellowish discoloration of the skin, mucous membranes, and whites of the eyes.

Because the spleen is a site of red blood cell destruction, treatment of this type of anemia often includes splenectomy.

Spherocytic anemia is a rare type of hemolytic anemia in which an inherited trait results in the production of erythrocytes that are spheroid rather than biconcave. The combining form spher/o means round. The altered shape of these spherocytes makes them fragile and more likely to be destroyed.

2.7 Sickle Cell Anemia

Sickle cell anemia is a genetic disorder characterized by production of abnormal hemoglobin (HbS). The red blood cells containing HbS develop a distorted crescent shape, similar to the blade of a sickle (as depicted in the accompanying photomicrograph). Because of this distortion, these cells become fragile. They are recognized by the body as defective and for this reason are destroyed, leading to chronic anemia.

The combining form poikil/o means irregular, and an erythrocyte with an irregular shape is called a poikilocyte. Sickle cells and spherocytes are examples of poikilocytes. The condition of having irregularly shaped red cells is called poikilocytosis.

2.8 Micropathology of Sickle Cell Anemia

The gene that causes production of HbS is most frequently found in persons of African ancestry. In those who develop the disease, sickled erythrocytes tend to become trapped in small blood vessels, impeding blood flow to the body's tissues.

Acute episodes of sickling are known as sickle cell crises, symptoms of which include joint pain, abdominal pain, and painful swelling of the hands and feet. Because sickle cell anemia is incurable, treatment of the disease is aimed at alleviating the symptoms.

Some individuals inherit only one defective gene, making them carriers of the sickle cell trait. These persons may produce some sickling as well but in a mild form that may be asymptomatic.

2.9 Diagnosis of Specific Anemias

The specific diagnosis of various kinds of anemia is made by assessing a complete blood count (CBC), by studying the red blood cell morphology, or shape.

When sickle cell disease is suspected, electrophoresis is performed on the blood sample. In this procedure, an electric current is used to separate and identify the abnormal hemoglobin.

2.10 Polycythemia

Unlike the red blood cell disorders that involve a low red blood cell count, erythrocytosis is the term for any condition involving an abnormally high red cell count.

Polycythemia is a condition characterized by a marked increase in the numbers of RBCs, as seen in this illustration of polycythemia vera. The prefix poly- means many; cyt/o means cell; and -emia means blood condition.

The overproduction of red blood cells is linked to a stem cell abnormality that also causes increases in the numbers of white blood cells and platelets. The excessive quantity of formed elements in the blood increases its viscosity, its thickness and resistance to flow, congesting the body's tissues and organs. Treatment of polycythemia vera includes efforts to reduce the blood's volume and viscosity.

Phlebotomy, the incision of a vein for removal of blood, may be performed as a treatment to reduce blood volume to a normal level.

Many healthy individuals who live at high altitudes have elevated red blood cell counts and hematocrit levels. This condition—known as physiologic polycythemia—represents the body's attempt to compensate for the lower oxygen levels associated with high altitudes.

3.1 Hemophilia

Hemophilia is a hereditary bleeding disorder caused by a deficiency in one of the factors necessary for the blood to clot.

Approximately 80% of the cases of hemophilia result from an absence or deficiency of antihemophilic factor VIII. Those who are born with this deficiency have a prolonged coagulation time, the time required for venous blood to clot in a test tube, and a relative inability to form blood clots. Partial thromboplastin time (PTT), a test that assesses defects in the coagulation pathway, is also prolonged in hemophilia.

Hemophilia is characterized by persistent bleeding from minor trauma, repeated episodes of spontaneous bleeding into the joints, excessive bleeding following dental procedures, and life-threatening hemorrhages.

3.2 Thrombocytopenia

You'll recall that in Section I we explored the role of platelets in the clotting process. Disorders that cause thrombocytopenia, a reduction in the normal number of platelets, can result in prolonged bleeding with minor trauma and spontaneous bleeding in the absence of any identifiable injury.

This condition is also called thrombopenia. You will recall that the combining form thromb/o means thrombus, a blood clot that obstructs a blood vessel or a cavity of the heart. The suffix -penia means deficiency. Therefore, thrombopenia is a deficiency in the number of platelets in the circulating blood.

3.3 Platelet Destruction and Splenectomy

Thrombocytopenia may be caused by decreased platelet production or increased platelet destruction. Platelet destruction may be drug-induced or may result from chemicals, radiation, or cancer. The most common etiology involves production of an autoantibody that attacks platelet antigens.

Because the spleen is a site of platelet destruction, splenectomy and administration of drugs to interfere with antibody synthesis are the primary treatment modalities. Splen/o means spleen and the suffix -ectomy means removal of or excision.

3.4 Thrombosis

The process of clot formation in blood vessels is called thrombogenesis, and the condition of a clot in a vessel is called thrombosis.

Thrombogenesis is favored by two conditions: slower than normal blood flow and rough spots along the lining of the blood vessel. Under these conditions, cellular elements and platelets accumulate and the clotting process begins. If allowed to continue, the clot may enlarge, impeding or completely interrupting blood flow.

An anticoagulant is a substance that prevents clotting. Just as the elements in the clotting process prevent blood loss with injury, anticoagulants in the blood help to preserve its fluid state. The importance of these anticoagulant substances comes into play when clots form in unhealthy blood vessels, as seen in the illustration.

Heparin, which is contained in basophils, is one example of a naturally occurring anticoagulant that works to inhibit intravascular thrombus formation.

The suffix -lysis means dissolving or destruction, and -lytic is used to form adjectives describing that same action. Thus, thrombolysis is the dissolution or destruction of a clot, and thrombolytic refers to something that is capable of dissolving a clot.

3.5 Leukopenia and Leukocytosis

Up to this point, we've looked at diseases affecting the red blood cells and disorders involving the clotting ability of the blood. Another large category of blood disorders includes those associated with the white blood cells.

For instance, leukocytopenia or leukopenia is a deficiency in the number of white blood cells (-penia means decreased or deficient).

Leukocytosis is a transient increase in the number of leukocytes in the blood. Leukocytosis is an indication of an infection or infectious process. The body increases the production of leukocytes to help fight the infection. For example, a high white cell count is an important diagnostic sign of appendicitis when it accompanies pain in the right lower quadrant of the abdomen.

3.6 Leukemia

Leukemia is a general term that refers to a variety of malignant white blood cell diseases. The word part leuk/o means white, and the suffix -emia, as we have seen, means blood condition. All of the leukemias involve replacement of normal bone marrow with proliferating leukocytes and their stem cells. The leukemic cells then leave the bone marrow, enter the circulation, and infiltrate the lymph nodes, spleen, liver, and other parts of the body.

3.7 Threaded Case Study: Acute Leukemia

Based on Li Chen's last white blood cell differential, his physician suspects that Li may have a type of leukemia. A diagnosis of leukemia is made with blood tests and bone marrow biopsy.

Let's review what takes place in the white blood cell count. The number of leukocytes per cubic millimeter is counted and a white blood cell differential is performed to determine the numbers and maturation of different kinds of leukocytes.

Types of leukemia are identified according to the specific proliferating white blood cell, the clinical course, and the duration of the disease.

Acute leukemia usually has a sudden onset, a rapid progression, and large numbers of undifferentiated, immature leukocytes in the blood. In acute myelogenous (myelocytic) leukemia (AML), there is a marked increase in the number of immature granulocytes (Fig. A). Acute lymphocytic leukemia (ALL) is characterized by proliferation of immature lymphocytes (Fig. B).

3.8 Chronic Leukemia

Chronic leukemias develop slowly. Chronic myelogenous (myelocytic) leukemia (CML) (Fig. A) is marked by the presence of excessive numbers of immature and mature granulocytes in the bone marrow and bloodstream. In chronic lymphocytic leukemia (CLL) (Fig. B), small lymphocytes—predominantly B cells—proliferate in the bone marrow, blood, liver, and lymphoid organs.

3.10 Threaded Case Study: Li Chen

As you'll recall, Li's blood tests showed elevated levels of lymphocytes. Several disorders are a possibility for Li. His doctor is now recommending a bone marrow biopsy to determine whether Li has CML.

3.11 Threaded Case Study: Chronic Myelogenous Leukemia (CML)

Li Chen is diagnosed with chronic myelogenous leukemia (CML). His treatment will involve the use of chemotherapeutic drugs, radiation therapy, and, possibly, bone marrow transplantation. The goal of treatment is to attain remission, that is, disappearance of the signs and symptoms of the disease.

After remission is achieved, Li will still have periodic checks for an extended period of years. Detection of leukemic cells, after an apparent recovery from the disease, signals the occurrence of a relapse. Without treatment, Li's disease would ultimately progress to an accelerated acute phase, leaving him only a few months to live.

The good news for Li is that, even without remission, the oncologist is confident that he will remain in this more manageable chronic phase of the disease for 2 to 4 years and that this can be well-controlled with treatment.

Section III: Classification of Disease

1.1 Organic and Functional Conditions

There are several ways to classify diseases, and these classifications help us to organize how we think and learn about disease processes.

One way to classify disease is to divide conditions into two categories according to whether the condition produces physical change in an organ or tissue. When the disease produces a demonstrable change such as a rash or a tumor, it is classified as an organic disease. When there is no such physical change, the condition is said to be functional; that is, there is an abnormal change in body function, but there are no physical signs or symptoms of disease. Psychological ailments are typically categorized as functional.

1.2 Classification by Cause

A very common way to classify diseases is by the general nature of their causes. These categories include infectious diseases (those caused by pathogenic organisms), hereditary conditions that are associated with the genetic makeup of the individual, degenerative conditions that involve deterioration of structure or function, traumatic conditions caused by injury, and nutritional diseases that occur in the absence of adequate nourishment.

Also included in this group of classifications are autoimmune diseases that result when the body produces an immune response against itself. The prefix auto- means self. An autoimmune disease is an altered function of the body's immune system that results in the production of antibodies that act against one's own cells. Rheumatoid arthritis and systemic lupus erythematosus (SLE) are examples of autoimmune diseases.

The combining form idi/o means individual or unknown. Thus, an idiopathic condition is one for which the cause is unknown. Idiopathic scoliosis, for example, is a curvature of the spine that appears most commonly in teenage girls and has no known cause.

1.3 Classification by Circumstance

Another means of classifying diseases is to identify the circumstances under which the disease occurs. For example, an iatrogenic condition is one caused by treatment, diagnostic procedure, or other action of the physician. The combining form iatr/o means physician or treatment. An unfavorable response to treatment, such as an allergic response to a prescribed medication, is an example of an iatrogenic disorder.

A nosocomial condition is one that is acquired while in the hospital. The most common of these is nosocomial infection, a hospital-acquired infectious disease process, such as the infection of a surgical wound. The combining form nos/o means disease.

Note that it is common to categorize a single condition by several different methods of classification at once. For example, if a patient fell out of bed in the hospital and broke the hip, the condition could be described as functional, nosocomial, and traumatic.

1.4 Pathogens

You will recall that the combining form path/o means disease and that -genic is a suffix that means either producing or produced by. In the term pathogenic, the suffix means producing, so a pathogenic microorganism is a very tiny living thing that causes disease; pathogenic microorganisms are also called pathogens. The degree of a microorganism's ability to cause disease is called virulence. Another term that means virulence is pathogenicity.

Microbiology is the branch of science that is concerned with the study of microorganisms.

There are various types of microorganisms, including bacteria, fungi, viruses, and protozoa.

1.7 Bacteria

Bacteria (sing., bacterium) are small single-celled microorganisms with a cell wall and an atypical nucleus that lacks a membrane; they commonly multiply by cell division.

The combining form bacteri/o means bacteria. It is used to form such terms as bacterial, meaning pertaining to or caused by bacteria.

Most bacteria are not pathogenic. Some live on or within our bodies without causing disease and are referred to as normal flora. They aid in digestion and skin preservation and provide protection from other microorganisms.

Some bacteria, however, are very virulent pathogens. We will consider some of them as we continue with this lesson.

1.8 Classification of Bacteria

Bacteria are classified according to their morphology, or shape. They occur as rod-shaped bacilli, spiral shapes including spirochetes and spirilla, spheroid (globe-shaped) cocci, and comma-shaped vibrios.

Bacteria are further classified according to how they respond to a special staining technique called a gram stain or Gram's stain. Bacteria in a smear on a microscope slide are treated with the gram stain and turn a dark violet or purple color. After staining, the slide is treated with alcohol. Bacteria are identified as gram-positive if they retain the dye when treated with alcohol; if the alcohol washes out the dye, the bacteria are classified as gram-negative.

A third means of classifying bacteria involves a different staining process. The bacteria are stained, heated, and treated with an acid to remove the color. If the bacterium resists decolorization, it is classified as acid-fast positive, often simply called "acid fast." If decolorization occurs, the bacterium is acid-fast negative.

The combining for aer/o means oxygen or air and the term aerobic refers to the need for oxygen. With respect to a cell or organism, aerobic means that oxygen is required to maintain life and growth. An aerobic process is one that occurs in the presence of oxygen.

Bacteria can be grouped based on their oxygen requirements. Some require oxygen to grow and are called obligate aerobes, while others will not grow in the presence of oxygen and are called anaerobes. Bacteria that can adapt and grow under either aerobic or anaerobic conditions are called facultative organisms.

1.9 Bacilli

Bacilli (sing., bacillus) are rod-shaped bacteria. The combining form that indicates bacilli is bacill/o.

Bacilli can be classified according to how the cells are grouped. They may occur as single cells, in pairs, or in chains.

Escherichia coli, often referred to simply as E. coli, is a gram-negative bacillus. E. coli is found as part of the normal flora of the digestive tract but may cause infections in other parts of the body, for example, if it comes in contact with a wound. There are various strains of this bacillus. A particularly pathogenic strain of E. coli is O157:H7, which is found in the feces of certain livestock and can cause severe gastrointestinal infection if ingested with contaminated water or improperly prepared food. The severe diarrhea that occurs with this condition can lead to renal failure and death if not successfully treated.

Tuberculosis is caused by the bacillus Mycobacterium tuberculosis, which is acid-fast. The abbreviation for acid-fast bacillus is AFB. There are other bacilli of the mycobacterium species that cannot be distinguished on a smear from the tuberculosis bacillus, but they do not cause contagious disease. Although some may infect humans with a compromised immune system, few are pathogenic to humans. Therefore, the presence AFB in sputum is usually a positive test for tuberculosis.

The bacterium that causes tetanus, Clostridium tetani, is an anaerobic bacillus. Tetanus is a potentially lethal infection of the central nervous system that is usually contracted through a wound.

1.10 Cocci

The spheroid bacteria called cocci (sing., coccus) can also be classified according to how the cells are grouped. They may occur as single cells, in pairs, in chains, or in clusters.

When cocci occur in pairs, they are classified as diplococci. You will recall the prefix diplo- means double. The bacteria that cause the sexually transmitted disease (STD) gonorrhea are diplococci.

Cocci that occur in chains are called streptococci. The combining form strept/o means twisted. In spite of its word origin, the term streptococcus does not necessarily mean that the chains of bacteria are twisted. Figure A illustrates a streptococcal colony on blood agar.

Streptococcal means pertaining to or related to streptococci and is often referred to in the shortened form "strep"; streptococcal pharyngitis is the term for inflammation of the throat pharynx (pharyng/o) caused by streptococci, in other words, strep throat.

Staphylococcus is the term for spheroid bacteria that occur in clusters. Note the spherical clusters of Staphylococcus aureus growing in blood agar (Fig. B). Staphyl/o is the combining form that means cluster; it also refers to the uvula, the soft tissue projection that hangs down at the back of the roof of the mouth.

Staphylococcal means pertaining to or related to staphylococci and is sometimes referred to in the shortened form "staph."

1.11 Spirochetes

Both spirilla and spirochetes are spiral-shaped bacteria. The spirochete called Treponema pallidum is the causative agent of the sexually transmitted disease (STD) syphilis.

A special technique called darkfield microscopy may be used to identify these spirochetes in a sample of fluid or tissue from the painless sore called a chancre. A chancre is the primary lesion of syphilis and occurs at the entry site of the infection. Several other laboratory tests can also be used to diagnose syphilis by identifying antibodies to the disease in the blood.

1.12 Vibrios

Vibrios are comma-shaped bacteria that are responsible for several kinds of gastrointestinal infections. Cholera, and several other epidemic forms of gastroenteritis, is caused by these bacteria. You will recall that gastr/o means stomach, enter/o means intestines, and -itis is a suffix that means inflammation; therefore, gastroenteritis is an inflammation of the stomach and intestines. You might also recall from Module 2 that gastroenteritis is likely to be treated by a gastroenterologist.

1.14 Fungi

Fungi (sing., fungus) occur as single-celled yeasts or as long, branched, filament-like structures called molds that are composed of many cells. Yeasts reproduce by forming buds, while molds reproduce by spore formation. There are more than 100,000 diverse species of fungi, many of which serve useful purposes. They are a key ingredient in the production of alcoholic beverages, are responsible for the flavor of cheese, give bread its lightness, and produce the antibiotic penicillin. Fungi are also important in nature because they help decompose dead plants and animals, making these complexes available for plant growth.

Some species of fungi are destructive to products made of natural materials like wood and leather, while others cause diseases in plants, animals, or humans. Fungi cause skin infections in humans, such as athlete's foot and ringworm, and respiratory infections, such as histoplasmosis and coccidioidomycosis. Fungi also cause opportunistic infections such as Pneumocystis carinii pneumonia (PCP) and pharyngeal and esophageal candidiasis in individuals with compromised immune systems.

1.15 Protozoa

Protozoa (sing., protozoan) are complex single-celled animals that generally exist as free-living organisms; a few are parasitic and live within the human body. They may be classified as motile (moving) or nonmotile. If motile, they are further classified by the way in which they move. Some move by changing their shape to form pseudopods (false feet); others move using flagella, whiplike formations that move the cell, or cilia, fine, hairlike projections that propel the organism.

Most parasitic protozoa produce some type of resistant form, such as a cyst, to survive in the environment outside the host. Other protozoa have complicated life cycles involving alternate existence in the human body and in insect vector. This is true of the protozoa that cause the tropical disease malaria. Several species of the protozoan plasmodium cause various types of this disease. During part of their life cycle they develop in Anopheles mosquitoes; they are spread when the mosquitoes bite humans.

Protozoa can infect the gastrointestinal, genitourinary, respiratory, and circulatory systems. Common protozoal diseases include amebiasis, giardiasis, toxoplasmosis and trichomoniasis.

1.16 Viruses

Viruses are subcellular organisms and are among the smallest known disease-causing microorganisms. Because of their small size, they must be viewed with an electron microscope. A fully developed viral particle, called a virion, is made up of genetic material, DNA or RNA, which is protected by an outer protein coating called the capsid. The capsid may be covered by a lipoprotein envelope that has projecting spikes. Enveloped viruses such as influenza, human immunodeficiency virus (HIV), and hepatitis B use these spikes to attach to host cells. Some viruses such as the rhinovirus, the cause of the common cold, lack both the envelope and spikes, so the capsid assists this virus in attaching to the host cell. You may remember that the combining form rhin/o means nose.

Viruses cannot survive independently. A virus invades a host cell for which it has specificity, stimulating it to participate in the formation of additional virus particles. For example, the hepatitis virus attaches to receptor sites on a liver cell. Because viruses reside in and use the host cell to replicate, it has been difficult to create antiviral drugs that are not also harmful to the host cell. Only a few antiviral agents exist, and these are useful for only a limited number of viruses.

Other common viruses are the Epstein-Barr virus, which causes infectious mononucleosis, and varicella, which causes chicken pox and herpes zoster (shingles).

1.18 Disease Transmission

The invasion of the body by pathogenic microorganisms is called an infection, and diseases that are caused by pathogens are classified as infectious diseases. Most infectious conditions are also contagious; that is, they can be transmitted from one person to another. Another term that means contagious is communicable. There are several routes of disease transmission.

In the direct-contact mode, the host is touched by an infected person and the organisms are placed in direct contact with susceptible tissue. For example, syphilis and HIV infections may be contracted when infectious organisms from the mucous membrane of an infected individual are placed in direct contact with the mucous membrane of a susceptible host.

Droplet transmission occurs when an infected individual coughs, sneezes, or speaks near a susceptible host. This mode of transmission requires that the two individuals be within a few feet of each other. Colds and influenza (flu) are spread in this way.

Microorganisms can also be transmitted via vehicles and fomites. Vehicles are substances such as contaminated food, blood, or water; the various types of hepatitis are vehicle-borne diseases.

Fomites are objects that are contaminated, such as a spoon or a tissue. Staphylococcus and other wound infections are often caused by contact with fomites. Nosocomial urinary tract infections are sometimes transmitted by way of contaminated urinary catheters.

Microorganisms are also transmitted by vectors, animals, or arthropods (insects and similar forms). The mosquitoes that transmit malaria are examples of vectors.

Airborne transmission occurs as a result of dust containing spores or by means of droplet nuclei, extremely tiny particles containing microorganisms that remain after contaminated droplets have evaporated. These particles may remain suspended in the air for long periods. They are dispersed by air currents and may be inhaled by a susceptible host. Mycobacterium tuberculosis, rubeola (measles), and the varicella viruses are examples of airborne infections.

1.19 Systemic Infection

The term systemic means pertaining to or affecting the body as a whole. Therefore, a systemic infection is one that is present throughout the body.

The combining forms sept/i and sept/o refer to sepsis, the presence of microorganisms. Septic means pertaining to infection. Blood does not normally contain microorganisms, but pathogens are found in the blood stream when there is systemic infection. This serious condition is called septicemia. More specific terms are used to indicate the type of organism with which the blood may be infected; for example, bacteremia refers to the condition of bacteria in the blood.

1.20 Prevention and Treatment

Prophylaxis is a term that refers to an intervention aimed at prevention of or protection against disease. The suffix -phylaxis means protection. Prophylactic means pertaining to prophylaxis.

Prophylactic measures that help to reduce the spread of infectious organisms include the use of antiseptics, bacteriostatic substances. You will recall that the prefix anti- means against, so antiseptic means against infection and refers to an agent that works to inhibit the growth and production of microorganisms. The suffix -static means inhibiting or controlling, so a bacteriostatic substance is one that controls or inhibits the growth of bacteria.

The suffix -cidal means pertaining to killing, so a bacteriocidal agent is one that is destructive to bacteria.

These agents are effective in helping to maintain an antiseptic environment and reduce the transmission of disease. The single most important prophylactic measure, however, is hand hygiene. Frequent handwashing or the use of antiseptic alcohol rubs is very effective in reducing the likelihood that you will contract an infectious disease or transmit an infection to someone else.

2.1 Weapons of Mass Destruction

Since the development of the atomic bomb during World War II, weapons of mass destruction (WMD) have been a cause of worldwide concern. With the attack on the World Trade Center in New York and the Pentagon in Washington D.C. on September 11, 2001, terrorism became a primary concern of the United States government.

The Federal Emergency Management Agency (FEMA) and the Centers for Disease Control and Prevention (CDC) have developed six lettered categories to classify weapons of mass destruction:

B		Biological
N		Nuclear (use of radioactive materials)
I		Incendiary (flammable substances used to ignite fires and explosives)
C		Chemical
E		Explosive

2.2 Pathogens as Weapons

Soon after the 9/11 attack, another terrorist act involved the sending of anthrax through the U. S. mail, causing illness and death, contamination of postal facilities, and nationwide concern. This type of terrorism is called bioterrorism because it involves the use of microorganisms, living weapons, to spread disease and fear among the population. You will recall that the combining form bi/o means life.

The characteristics of pathogens that place them in a risk category with respect to national security are those that have the potential to cause panic and social disruption because they can be easily disseminated or are readily contagious, and that could have a significant public health impact by causing widespread illness and death.

Although health care providers must be trained to deal with emergencies caused by all weapons of mass destruction, it is particularly important that they be trained to recognize and treat the conditions that may be caused by microorganisms from a bioterrorism attack.

2.3 Pathogenic Agents of Bioterrorism

The CDC lists the highest priority agents of potential bioterrorism as those that cause anthrax, botulism, plague, smallpox, tularemia, and viral hemorrhagic fevers.

Anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax most commonly occurs in animals such as cattle, sheep, goats, camels, and antelopes, but it can also occur in humans.

Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the anaerobic spore-forming bacterium Clostridium botulinum. Food-borne botulism can be especially dangerous because many people can be poisoned by eating a contaminated food.

Plague is also known as bubonic plague or black plague. It is an infectious disease of animals and humans caused by a bacterium named Yersinia pestis. It is vector-borne by rodent fleas. People usually get plague from being bitten by a rodent flea that is carrying the plague bacterium or by handling an infected animal. Millions of people in Europe died from plague in the Middle Ages, when human homes and places of work were inhabited by flea-infested rats. Today, modern antibiotics are effective against plague, but if an infected person is not treated promptly, the disease is likely to cause serious illness or death.

2.4 Additional Pathogens with Bioterrorism Potential

Smallpox is a serious, contagious, and sometimes fatal infectious disease. There is no specific treatment for smallpox, and the only prevention is vaccination. Smallpox was declared globally eradicated in 1980 and vaccination of the population was discontinued. With current concerns that the smallpox virus could be used for bioterrorism, strategies are under development to protect the American public should this disease be brought back as a bioterrorism weapon.

Tularemia is an infection by the bacterium Francisella tularensis that is common in wild rodents. It is also called deerfly fever and rabbit fever. There are several possible modes of transmission, but it is most commonly transmitted to humans by contact with animal tissues or ticks. As a bioterrorism agent, an aerosol release would be the most likely method of spreading this organism. It would result in a large number of pneumonia cases within several weeks after exposure.

Viral hemorrhagic fevers (VHFs) are a group of diseases caused by four different groups of viruses. They affect multiple body systems; characteristically, the overall vascular system is damaged and the body's ability to regulate itself is impaired. These symptoms are often accompanied by hemorrhage. Some of these viruses are spread by tick and mosquito vectors; the hosts of others are unknown. The Ebola and Marburg viruses are well-known examples.

3.1 Immunity

In an earlier lesson of this module you learned how leukocytes play a significant role in the body's ability to protect itself from foreign organisms and substances.

Let's turn our attention now to the broader subject of immunity, the body's ability to protect itself from harmful pathogens and disease.

We are constantly exposed to pathogens, microorganisms that are capable of causing disease. Note that this term contains path/o, meaning disease, and -gen, a suffix that means producing or forming.

The body's ability to counteract the effects of pathogens is called resistance and lack of that resistance is called susceptibility.

Resistance may be either specific or nonspecific; that is, directed against specific pathogens or against the general invasion of disease organisms.

The immune system has an array of defenses against these organisms. Nonspecific defenses include the skin and mucous membranes, the lymph organs, leukocytes, antibodies, and macrophages. The protein interferon provides resistance to some viruses.

The skin and lymph organs are discussed in other modules. We've already seen what macrophages can do, so in this lesson, we'll focus on the general process of immunity and some of the terminology associated with this subject.

3.2 Natural Immunity

Immunity may be categorized as natural or acquired. Natural immunity is present at birth; its development does not require previous exposure to a disease-producing substance. Natural immunity results in a nonspecific defensive reaction against any foreign organism.

You will recall from Section I, Lesson 2 that blood plasma consists mainly of water and proteins. Among the proteins are the globulins—categorized as alpha, beta, and gamma—that serve as defense mechanisms of the immune system. Specific gamma globulins called immunoglobulins provide natural, nonspecific protection. These special proteins fight disease by recognizing and destroying antigens—harmful or abnormal substances such as bacteria and viruses.

This occurs as the result of a series of responses. To begin with, when harmful bacteria enter the body and cause tissue damage, inflammation—characterized by heat, redness, pain, and swelling—helps to contain the infection and to promote a return to normal by stimulating the arrival of white blood cells to the injured site. The first to arrive are the eosinophils, which have phagocytic capability.

3.3 Acquired Immunity

Acquired active immunity results when the presence of a disease generates the production of antibodies. These special protein molecules provide specific protection from further infection.

This type of immunity can also be acquired by receiving a vaccination—a modified form of disease toxin called a toxoid. This term is from tox/o, meaning poison, and the suffix -oid, meaning like or resembling.

Vaccines induce antibody production without causing the harmful effects of the original toxin. Thus, vaccination is a form of prophylaxis, a preventive measure against disease.

A third way to acquire active immunization is by transfer, such as in bone marrow transplant.

Acquired passive immunity occurs when preformed antibodies are received from an animal or another person to obtain protection from disease. Transfer of antibodies from mother to fetus across the placental membrane is one example of acquired passive immunity.

3.4 Specific Defense (animation)

Specific defense incorporates both cell-mediated immunity and antibody-mediated immunity. The leukocytes play a significant role in both types.

T-lymphocytes, or T cells, are responsible for the cell-mediated response, and B-lymphocytes, or B cells, are responsible for antibody-mediated responses.

3.5 Allergy

Allergies are conditions in which the body reacts with an exaggerated immune response. In an allergic reaction, some injured leukocytes release a substance called histamine, which causes dilation of the capillaries, increased gastric secretion, and contraction of smooth muscle in several internal organs.

Histamine is responsible for the symptoms of hay fever; a medication that acts against it is called an antihistamine.

Basophils, the leukocytes responsible for producing histamine, are also active in fighting parasitic infections. Eosinophils increase in number to help the body protect itself from allergens, substances that can cause allergic reactions.

Occasionally, interaction of a defense mechanism and an antigen causes injury due to the excessive production of histamine; this is called hypersensitivity. A life-threatening hypersensitivity response is called anaphylaxis, which occurs in response to a previously encountered antigen. In these extreme reactions, capillary dilation causes hypotension and shock, while smooth muscle contraction may constrict the bronchi, restricting respiration.

4.1 Medical Records

Effective documentation of information about patients and their care marks the professional who recognizes efficient record keeping as a way to meet ongoing patient needs. Medical records provide important communication to other health professionals, insurance companies, and governmental agencies.

There are many types of medical records, and their format will differ depending on their purpose, preferences of the facility, and whether the patient is treated as an inpatient (IP), one who is admitted to the hospital for a period that includes at least one overnight stay, or an outpatient (OP), one who receives care at the hospital, clinic, or other health facility but is not admitted for an overnight stay.

Individuals professionally qualified in the management of patients' records may have various qualifications, titles, and responsibilities. Titles include medical record librarian, medical record technician, and medical record administrator. Duties may include planning, designing, and managing systems for patient administrative and clinical data as well as the management of patient medical records.

4.2 The Medical Chart

The records pertaining to each patient are usually kept all together in one place, called a chart. The chart may be a group of paper documents or a computer file.

The documents in a chart include a cover page that states the patient's legal name, date of birth (DOB), address, social security number (SSN), the attending physician's name, contact information for the next of kin, and identification of the patient's parent or legal guardian if the patient is a minor or is not competent. For inpatients, this document is often the admitting form, which also includes the patient's signed consent to treatment.

4.3 Chart Contents

A medical chart contains a report of the patient's medical history and physical examination, abbreviated H & P, for history and physical. Reports of consultations and diagnostic tests and copies of correspondence relating to the patient are all kept in the chart. Emergency room treatment reports, surgical reports, and reports of any procedures performed on the patient are included as well. Inpatient charts will have separate sections for keeping ongoing records of vital signs and for documenting the administration of medications. Chart notes by physicians include observations and orders for care and procedures. Chart notes by nurses include documentation of orders carried out and observations pertinent to patient care.

The term charting refers to the process of adding any information to a medical record. All written records that you initiate must be accurate, pertinent, and legible.

4.4 Confidentiality

Confidentiality has always been a cardinal concept of medical ethics. Medical information is considered confidential and should only be shared with those who have a legitimate need for the information.

The Health Insurance Portability and Accountability Act (HIPPA) is a federal law that became effective in 2003. It gives patients rights with respect to their health records, including the right to restrict access to confidential information and the right to receive confidential information that is in their own records.

Module 8

Introduction

This module is the first in a series devoted to individual body systems. In this module, you will learn more about the medical terms associated with the cardiovascular and lymphatic systems. When you complete this module, you should be familiar with the terms that describe the anatomy of those systems and have a good understanding of terms that specify disorders affecting them. You will be able to recognize terms for tests that are used to diagnose disorders of the cardiovascular and lymphatic systems. You'll also learn about the therapeutic measures used to treat these conditions, including the categories of drugs that improve cardiac and lymphatic function. As you work through this module, you may need to refer to the basics of word structure that were introduced in Module 1.

Remember that this integrated learning program is intended as a supplement to your text—not as a substitute. Be sure to keep your text available for ready reference.

Objectives

In this module, you will learn to:

• Recognize names of the structures of the cardiovascular system and define terms associated with these structures.
• State the function of the lymphatic system and analyze associated terminology.
• Label the major structures of the lymphatic system.
• Write the meaning of word parts associated with the cardiovascular and lymphatic systems and use the word parts to build and analyze terms.

Section II Cardiovascular System

1.1 Threaded Case Study: Fred

Before we begin to explore the anatomy of the cardiovascular system, let's meet Fred Sibley. Fred is a 34-year-old man who's visiting with his doctor today to report some recent health problems.

Fred mentioned to his doctor that he's had "some swelling" in his throat. He said he is often fatigued and has recently noticed an unintended drop in his weight. He also complained of occasional periods of rapid heart beat.

Fred will undergo a thorough physical assessment to help his doctor understand the cause of these complaints. As we learn more about Fred's health problems, we'll be able to see the cardiovascular and lymphatic systems at work.

1.2 Cardiovascular Blood Flow (animation)

The cardiovascular system consists of the heart and a closed network of blood vessels that carry blood throughout the body. This system transports nutrients and oxygen to the cells to power the body's many functions. The blood vessels also carry carbon dioxide and waste products to the lungs and kidneys to be eliminated. You'll notice two important combining forms in the term cardiovascular: cardi/o, which means heart, and vascul/o, which means vessel.

1.3 External View of the Heart

The heart is the muscular, cone-shaped organ that serves as the pump of the cardiovascular system. It is approximately the size of a closed fist. The heart is almost 5 inches in length, about 3 inches wide at its broadest part, and slightly more than 2 inches in depth. It weighs an average of 10 ounces in men and 8 ounces in women.

1.4 Location of the Heart

The heart lies between the lungs in the mediastinum of the thoracic cavity. The term mediastinum is built from the combining form mediastin/o, meaning middle region.

Behind the heart are the esophagus, major blood vessels, and the spinal column. The heart rests on the diaphragm and is rotated to the left.

1.5 Layers of the Heart Wall

The heart wall has three distinct layers. The endocardium—the inner layer—is made of smooth membranous tissue. The endocardium lines the interior of the heart and the heart valves. The thick middle layer of the heart wall is called the myocardium; it is composed of cardiac muscle. The epicardium is the thin outer layer of the heart wall. At the lower, more pointed end of the heart, the epicardium becomes continuous with the loose-fitting, double-layered sac called the pericardium, in which the heart is encased.

1.6 Terms Pertaining to Layers of the Heart Wall

Analyzing the word parts in the terms that designate the layers of the heart wall will help you remember their definitions. In each of the terms—endocardium, myocardium, epicardium, and pericardium—we see the combining form cardi/o, which, as you know, means heart. The suffix -ium, which also appears in each of the terms, is defined as membrane.

The job of distinguishing these terms, therefore, falls to the prefixes. The prefix endo- means inside, thus the endocardium is the inner layer of the heart. The combining form my/o, which means muscle, refers to the muscular layer—the myocardium. The epicardium is the outermost layer, indicated by the prefix epi-, meaning upon or above.

The prefix peri- means around; therefore, pericardium is the term for the sac that encloses the heart.

1.7 Chambers of the Heart

The heart has four chambers. The two upper chambers are called the atria (sing., atrium); the lower two are the ventricles. The left and right atria are abbreviated LA and RA, respectively; the abbreviations for the ventricles are similarly LV and RV.

The atria receive blood returning to the heart from the veins throughout the body. The ventricles pump blood from the heart, through the arteries to the body's tissues. The combining forms atri/o and ventricul/o refer, respectively, to the atria and ventricles.

The left and right sides of the heart are separated by the cardiac septum. This term contains the combining form sept/o, meaning partition.

1.8 Cardiac Valves

The upper and lower chambers of the heart are connected by valves that keep the blood flowing in one direction. The combining forms that mean valve are valv/o and valvul/o. Thus, valvar and valvular are terms that mean pertaining to a valve.

The tricuspid valve connects the right atrium and the right ventricle; the mitral or bicuspid valve connects the left atrium and left ventricle. Together the tricuspid and bicuspid valves are known as the atrioventricular (AV) valves.

The pulmonary valve is located between the right ventricle and the pulmonary artery. The aortic valve connects the left ventricle and the aorta. These two valves are called the semilunar valves.

1.9 Coronary Arteries

The systemic circulation supplies blood to the heart muscle by means of the coronary arteries. The term coronary is based on the combining form coron/o, which means crown, because these arteries encircle the heart like a crown.

Because of the common association between the heart and the coronary arteries, the combining form coron/o has also come to mean heart, and coronary means pertaining to the heart.

1.10 Systemic vs. Pulmonary Circulation (animation)

The circuit that the blood follows from the heart to the body's organs and back is called the systemic circulation. The combining form system/o means system and in this case refers to the general circulation of the blood throughout the body.

The pulmonary circulation is the blood's route from the heart through the lungs, where it receives a fresh supply of oxygen, and back to the heart.

You will recall that pulmon/o is a combining form that means lung.

1.11 Systole, Diastole

Blood is forced through the circulatory system by the rhythmic contraction and relaxation of the heart. This pumping activity occurs in three phases that constitute the cardiac cycle. The three phases are atrial contraction, ventricular contraction, and rest.

Systole is the term for the phases of the cardiac cycle when the heart contracts. This term usually applies specifically to ventricular contraction.

Diastole is the period during which the heart relaxes between contractions.

The heart pumps about 5 quarts of blood a minute, 75 gallons an hour, and about 2000 gallons a day.

1.12 Heart's Electrical Conduction (animation)

The myocardium consists of two types of cardiac muscle tissue: contracting tissue and conducting tissue.

The heart's contractions are generated by a tiny electric current called the cardiac impulse that travels along pathways in the conducting tissue. This electrical wave coordinates the series of muscular contractions that occur in the contracting tissue during the cardiac cycle.

The cardiac impulse begins in the right atrium in conducting myocardium called the sinoatrial (SA) node that serves as the heart's pacemaker. The impulse spreads in circular waves over the atrial walls, causing the atria to contract. The impulse then passes through the atrioventricular (AV) node, a second area of conducting myocardium. From this node, it passes through a band of conducting muscle that connects the atria to the ventricles and is called the bundle of His. The bundle of His divides into the left and right bundle branches, conducting the cardiac impulse to the left and right ventricles. The bundle branches further divide into Purkinje fibers, fine strands of conducting muscle that transmit the impulse to the contracting muscle of the ventricles. This diagram illustrates the electrical conduction system of the heart.

1.14 Threaded Case Study: Fred

Now that we've looked at the structure and function of the heart, we'll move on to explore the anatomy of the blood vessels. But first, let's visit with Fred, whose doctor has begun the physical examination. The physician is gathering a wealth of data about the function of Fred's heart and blood vessels. Fred will describe his personal health habits, review his health history, and be encouraged to recall any additional symptoms he has experienced. We'll return soon to see how his exam is progressing.

1.15 Relative Size of Blood Vessels

There are three major types of blood vessels: arteries, veins, and capillaries.

Arteries carry blood containing oxygen and other nutrients away from the heart to the body's cells. Because they need to withstand the force of the blood as it leaves the heart, the arteries are large, strong vessels with elastic walls. The largest artery in the body is the aorta, indicated in medical terms by the combining form aort/o. Aortic means pertaining to the aorta.

The suffix -ole means small. Arterioles are small arteries that carry blood from the larger arteries to the tiniest of the blood vessels, the capillaries.

1.16 Microcirculation

The capillaries are microscopic blood vessels with thin walls that permit the exchange of oxygen and nutrients from the blood into the interstitial fluid surrounding the body's cells. These tiny vessels also allow carbon dioxide and waste materials from the cells to pass into the blood from the interstitial fluid.

The oxygen-poor and waste-filled blood then passes from the capillaries to small veins called venules. The venules carry the blood to the veins, which transport it back to the heart.

Because venous return of blood to the heart is less forceful than blood flow through the arteries, the walls of the veins are thinner and less elastic. Valves in the veins keep the blood flowing toward the heart.

The largest veins in the body are called the venae cavae. The superior vena cava receives blood from the veins of the upper body and the inferior vena cava receives blood from the lower body. Both venae cavae connect with the right atrium of the heart.

1.17 Categories of Blood Vessels

Let's review some of the word parts that are used to refer to the blood vessels.

Angi/o and vas/o are combining forms that mean vessel; they may be used to indicate any of the three categories of blood vessels. You may recall that angiography refers to radiography of blood vessels using a contrast medium. Angioplasty is the term for repair or reconstruction of a vessel. The term vascular means pertaining to a vessel or to multiple vessels.

Arter/o and arteri/o refer specifically to the arteries. Arterial means pertaining to an artery or arteries. Arteriography is the term for x-ray imaging of arteries. By joining the combining form arteri/o to the suffix -ole—meaning little—we form the term arteriole, which you'll remember means small artery.

Three combining forms—phleb/o, ven/o, and ven/i—are all defined as vein. Both venipuncture and phlebotomy are terms for the procedure of entering a vein with a needle to draw blood for analysis or to inject medication. The combining form venul/o is used to build another familiar term, venule, meaning small vein.

2.1 Pulse Points

The force of the blood as it is ejected from the heart causes a regular expansion and contraction of the arterial walls called the pulse. These arterial pulsations can be felt at a number of sites on the body.

The most commonly used pulse point is over the radial artery on the anterolateral aspect of the wrist.

The pulse rate is the number of heartbeats per minute. The rate and quality of pulse are indicators of heart function. You will recall from Module 6 that the pulse rate is one of the vital signs that is part of a physical examination or routine physical assessment.

The normal pulse rate is between 60 and 100 beats per minute. Bradycardia—using the prefix brady-, which means slow, and the word root for heart—is defined as a slow heart rate of less than 60 beats per minute. Tachycardia, a term built from the same word root, but preceded by the prefix tachy-, which means fast, is a condition in which the heart beats faster than 100 beats per minute.

Using the second and third fingers of one hand, try to locate your radial pulse. Be aware that, with one pulsation, all the events in the cardiac cycle and the conduction process have just occurred.

2.2 Blood Pressure

Blood pressure is the force that the circulating blood exerts against the walls of the blood vessels. The measurement of blood pressure is one diagnostic indicator of health of the cardiovascular system. Blood pressure is determined by blood volume, the size and tone of the blood vessel, and the force of the heart's contraction as it ejects blood into the arteries.

Blood pressure is measured using a stethoscope and an instrument called a sphygmomanometer.

When measuring blood pressure, the stethoscope is used to hear the pulsation within an artery. You will recall from Module 6 that a stethoscope is an instrument used for auscultation, listening to the sounds of breathing and heartbeat within the chest. The combining form steth/o means chest.

2.3 Sphygmomanometer

The pressure in the aorta and large arteries of a healthy young adult is approximately 120 mm Hg (millimeters of mercury) during systole, when the ventricles are contracting, and 80 mm Hg during diastole, when the heart is relaxed. Both the systolic and diastolic pressures are measured and reported. Using the example above, the blood pressure would be written as 120/80.

Abnormally high blood pressure is called hypertension; when the blood pressure is lower than normal, it is described as hypotension.

2.4 Electrocardiography

Diagnosis of rhythmic irregularities of the heart is aided by a process known as electrocardiography, which records the heart's electrical activity. The record produced by electrocardiography is called an electrocardiogram (see illustration), an ECG or EKG. Because Fred has complained of occasional rapid beating of his heart, he will undergo an ECG.

A portable electrocardiograph, called a Holter monitor, can be worn by patients to record heart function over a long period of time and during various activities. This test aids in the diagnosis of cardiac problems that occur intermittently.

An ECG stress test, also called an exercise tolerance test, is used to evaluate whether the blood supply to the heart muscle is adequate. The ECG is monitored and recorded while the patient performs exercise, usually on a treadmill. The patient's blood pressure and pulse are also monitored during the test. Resting ECGs are usually performed both before and after the exercise portion of the test.

2.5 Nuclear Medicine Procedures

Another test used to evaluate the blood supply to the heart is the thallium test, a nuclear medicine scan, also called myocardial perfusion imaging. This test shows how well blood flows to and within the heart muscle.

The most common form of thallium test is called thallium stress testing. The patient performs exercise on a treadmill or bicycle. When the patient reaches his or her maximum level of exercise, a small amount of a radioactive substance called thallium is injected into the bloodstream through a vein in the arm. Then the patient lies on a special table and a gamma camera senses the radioactivity and maps its flow through the heart muscle. The scan may be repeated after several hours of rest or a resting scan may be recorded prior to the exercise.

Positron emission tomography (PET) scanning is another nuclear medicine procedure that uses radioactive material to evaluate the vascular perfusion of the heart.

2.6 Echocardiography

Echocardiography (ECHO), the use of high-frequency sound waves to visualize the structures and record the function of the heart, is another imaging modality used in the diagnosis of cardiovascular conditions.

Doppler ultrasound methodology allows recording of flow phenomena in color and permits demonstration of both arteries and veins. Doppler ultrasound is used extensively to detect vascular disease.

2.7 Angiography

Many radiographic procedures aid in the diagnosis of cardiovascular conditions. The chest x-ray (CXR) examination is a simple, noninvasive procedure that provides information about the size and configuration of the heart. As you will see in a subsequent lesson, heart problems can have a significant effect on the lungs as well, so x-ray images of the heart and lungs are valuable as a screening test and to monitor patients with heart problems periodically during the course of their treatment.

You'll recall that angiography is the process of obtaining radiographic images of the blood vessels following injection of a contrast medium. Angiography refers to a number of different procedures that also have specific names. For example, arteriography is radiographic imaging of arteries. Arteriography may be named more specifically for the artery visualized; for example, a coronary arteriogram is a study of the coronary arteries that supply the heart. Aortography demonstrates the aorta, and angiocardiography demonstrates the interior of the heart and the great vessels that connect to the heart. Phlebography and venography are terms that refer to the radiographic imaging of veins.

Computed tomography angiography (CTA) is a method of demonstrating blood vessels using the latest types of computed tomography (CT) scanners. Incredibly clear 3-dimensional images of major vessels can be obtained by this method. The illustration demonstrates a CTA image of the renal vessels.

Angioscopy is the visual examination of blood vessels using a fiber-optic microscope introduced via catheter. Angioscopy has been demonstrated to be very sensitive in detecting problems within arteries.

Experimental computer systems permit evaluation of vessels by means of virtual angioscopy using data input from other imaging methods.

2.8 Cardiac Catheterization (video)

In addition to procedures such as electrocardiography and echocardiography, cardiac catheterization provides several different approaches to the diagnosis and monitoring of heart disease.

Cardiac catheterization involves the placement of a flexible catheter in the heart. Catheters threaded through the aorta, as in this video, may be used to deliver a contrast agent for angiocardiography, to place a fiber-optic camera for angioscopy, or to perform angioplasty.

Specialty catheters can also be placed in the heart via an intravenous route. These catheters may be left in place and are used to monitor blood flow and pressure within the heart.

2.9 Magnetic Resonance Angiography (MRA)

Magnetic resonance imaging (MRI) uses radiofrequency waves and a strong magnetic field rather than x-rays to provide remarkably clear and detailed images of many structures within the body. Magnetic resonance angiography (MRA) is a specific application of magnetic resonance imaging used to produce pictures of the heart and blood vessels. MRA is unique in that it can create detailed images of blood vessels without the use of contrast material, but special MRI contrast agents are often used to enhance visualization of arteries. The accompanying illustration of an MRA demonstrates a large middle cerebral artery aneurysm (arrow).

2.10 Laboratory Tests

In addition to physical examination and imaging techniques, a variety of laboratory techniques help establish a diagnosis in cases of cardiovascular disease.

When a heart attack causes damage to the heart muscle, certain enzymes are released into the bloodstream and can be measured in laboratory tests. The tests are named for the enzymes they measure: lactate dehydrogenase test (LDH) and creatine kinase test (CK). The CK test is also called creatine phosphokinase test (CPK).

2.11 Laboratory Tests for Cardiovascular Risk Factors

Blood tests are also used to screen for risk factors such as high levels of substances called lipoproteins that transport lipids (fats) in the blood. There are three types of these substances: HDL cholesterol, LDL cholesterol, and triglycerides. HDL stands for high density lipoprotein, sometimes called the "good cholesterol," and LDL stands for low density lipoprotein, "bad cholesterol." The accompanying illustration demonstrates the structure of a lipoprotein.

High levels of these substances, especially LDL cholesterol, are known to be associated with an elevated risk of arteriosclerosis. This term is built from arteri/o, which you know means artery, and -sclerosis, meaning hardening, so arteriosclerosis is the condition of hardening of the arteries.

The condition of an abnormally high level of cholesterol in the blood is called hypercholesterolemia. When diet and exercise fail to adequately lower high cholesterol levels, medications in the class of antilipidemic drugs may be prescribed for this purpose.

3.1 Inflammatory Heart Conditions

We'll begin our review of cardiac pathology by considering infectious or inflammatory conditions that affect the heart. Some clues to help you identify this group of conditions will be the combining form cardi/o and the suffix -itis. By now, you're well aware that addition of that suffix to a word root indicates inflammation. Let's look at several of those terms now.

3.2 Endocarditis

Endocarditis is inflammation of the inner lining of the heart. Also known as bacterial endocarditis (pictured here), this disease occurs when microorganisms infect the endocardial surface.

Because the endocardium lines both the heart and the valves, endocarditis frequently affects the cardiac valves.

3.3 Pericarditis

Pericarditis is inflammation of the pericardium, the double-layered sac that encloses and protects the heart. Pericarditis may be caused by viral or bacterial infection. It may also be secondary to trauma or other illnesses.

One possible complication of pericarditis is the accumulation of blood or fluid in the pericardial space. If the amount of accumulated fluid becomes significant, the heart may become compressed. This condition is called cardiac tamponade. Pericardiocentesis is then performed to puncture the pericardial sac and aspirate the excess fluid.

Myocarditis, as you've probably guessed, is inflammation of the thick, muscular middle layer of the heart. This condition also can have a variety of causes.

3.4 Cardiovalvulitis

An inflammatory reaction can involve any structure in the cardiovascular system. Cardiovalvulitis is a condition characterized by inflammation of the heart valves. Note the presence of the combining form valvul/o, meaning valve.

Cardiovalvulitis may cause lesions to form on the valve leaflets, which then thicken, harden, and lose their mobility, a condition known as valvular stenosis. When the mitral valve undergoes these kinds of inflammatory changes, the condition is called mitral valve stenosis.

Both the term stenosis and the suffix -stenosis mean narrowing or constriction.

3.5 Valvular Insufficiency

Valvular insufficiency, also known as regurgitation, is often caused by inflammatory disease. This disorder is characterized by a backflow of blood from the ventricles into the atria because of failure of the valves to close properly.

Mitral valve prolapse is a kind of valvular insufficiency in which the leaflets, or cusps, of the valve protrude back into the left atrium during systole, allowing blood to flow backward.

3.6 Threaded Case Study: Heart Murmur

Another manifestation of valvular dysfunction, as well as of many other cardiovascular disorders, is the heart murmur, an abnormal, prolonged sound heard between normal heart beats.

Murmurs occur as a result of alterations in blood flow and/or structure of the heart or blood vessels. Here, the physician listens with a stethoscope to ensure that Fred's heart sounds are normal.

3.7 Angiocarditis

Now let's turn our attention to some terms that refer to disorders of the blood vessels. Angiopathy is a general term that describes any disease of the blood vessels.

Angiocarditis describes inflammation of the heart and the large blood vessels (see illustration). The combining form angi/o indicates the involvement of the blood vessels in the disorder.

Aortitis is a specific angiopathy characterized by inflammation of the aorta.

Phlebitis, sometimes called thrombophlebitis, is the inflammation of a vein. The word part thromb/o in that term tells us that phlebitis is often accompanied by the formation of a thrombus or blood clot.

3.8 Therapeutic Management

Therapeutic management of inflammatory cardiovascular disease typically consists of the administration of antibiotics and anti-inflammatory agents.

Depending on the severity and the degree of damage to the heart and/or vessels caused by infection, changes in life style—diet and physical activity, for example—may be required.

Surgical repair or replacement of damaged heart structures with prosthetic devices, such as the artificial valves shown in the accompanying illustration, may also be necessary.

3.9 Normal Heartbeat; Dysrhythmia (animation)

Earlier in this module, we talked about the regular, rhythmic contraction and relaxation of the heart muscle that forms the cardiac cycle. Each contraction of the heart is triggered by a wave of electricity that spreads across certain cardiac pathways and structures. Pathologic conditions of the cardiovascular system can cause the normal pattern of the heart's rhythm to be altered.

The terms dysrhythmia, and more commonly arrhythmia, are both used to refer to disturbances in the heart's normal rhythmic pattern. As you can see, both terms are built from combining forms that mean rhythm, rrhythm/o and rhythm/o.

3.10 Heart Block

Heart block occurs when there is a delay or interruption in conduction of the electrical impulse. The block is named specifically for the location of the blockage. For example, when the block occurs between the atria and the ventricles it is called an atrioventricular (AV) block and prevents impulses from reaching either ventricle. A right bundle branch block prevents impulses from stimulating the right ventricle, but the left ventricle is not affected.

This conduction delay or failure may happen intermittently or with such frequency that virtually no impulses reach the ventricles.

3.11 Atrial Flutter

Flutter is a type of arrhythmia characterized by rapid, but regular, contractions of the atria or ventricles. In atrial flutter, the heart rate may average between 250 to 350 beats per minute.

The subjective experience of a racing or pounding heart is called palpitations. Palpitations may occur as a result of emotional stress or may be associated with heart disease.

3.12 Fibrillation

Fibrillation (shown on the accompanying ECG strip) is an arrhythmia in which there is a marked disturbance of the heart's rhythm. Fibrillation is characterized by rapid, disorganized, and ineffectual contractions of the atria or ventricles. Severe alterations in the heart's rhythm, such as fibrillation, can result in cardiac arrest or asystole, the cessation of the heart's activity.

3.13 Treatment of Cardiac Arrhythmias

Cardiac arrhythmias may be treated in a variety of ways, depending on their type and severity.

Antiarrhythmic medications may be given alone or together with other forms of treatment.

Termination of the rapid, uncoordinated quivering associated with fibrillation is often accomplished by using a defibrillator, an electrical device that delivers a shock through the chest wall to the myocardium. This procedure, called defibrillation, helps to reestablish normal contraction rhythm in a heart that is not beating properly. The restoration of normal heart rhythm using electric shock is called cardioversion (Fig. A).

To maintain normal rhythm in instances of interference with the heart's electrical impulses, a cardiac pacemaker, a battery-powered device that initiates the heart beat, may be implanted (Fig. B).

3.16 Cardiomyopathy

Now that we've considered some examples of abnormal heart rhythms and inflammatory heart conditions, we'll look at a few other categories of heart and blood vessel disorders. First let's consider some general descriptors that apply to many cardiac disorders.

Cardiomyopathy is any disease of the heart muscle. Cardiomyopathic disorders primarily affect the structure and function of the myocardium.

Cardiomegaly, enlargement of the heart (see illustration), may be observed in a variety of disorders ranging from those present at birth to acquired conditions in which there is excessive demand on the heart's pumping ability.

3.17 Congenital Heart Disease

Congenital heart disease forms a third category of cardiac illness. Congenital heart disease refers to structural or functional abnormalities of the heart that are present at birth.

Septal defects, abnormal openings in the walls that separate the atria and ventricles, are examples of congenital heart disease (see illustration). When an abnormal opening is formed between the atria, it is called an atrial septal defect (ASD); a ventricular septal defect (VSD) is the term used when the opening is between the ventricles.

3.18 Additional Congenital Heart Conditions

Coarctation of the aorta (CoA) (Fig. A) is a congenital narrowing of the aorta, most commonly just distal to the area where vessels branch off to the left arm. This condition causes hypertension. Coarctation is the term for stricture or contraction of the walls of a vessel, particularly the aorta.

Patent ductus arteriosus (PDA) (Fig. B) is an abnormal opening between the pulmonary artery and the aorta caused by failure of the fetal ductus arteriosus to close after birth. This condition occurs most often in premature infants. The term patent means open or unobstructed. This condition permits blood to bypass the circulation to the lungs, decreasing the oxygen content of the blood. The defect often corrects itself within several months of birth but may require infusion of chemicals, the placement of "plugs" via catheters, or surgical closure.

Perhaps you recall from Module 5 that the prefix tetra- means four and that the tetralogy of Fallot (TOF) (Fig. C) is a group of four congenital heart abnormalities that quite commonly occur together. The four defects are:

1. ventricular septal defect
2. pulmonic stenosis (narrowing of the valve leading to the pulmonary arteries)
3. aorta "overrides" the ventricular septal defect
4. hypertrophy (thickening) of the right ventricle

In tetralogy of Fallot there is decreased flow of blood to the lungs and mixing of the blood from the two sides of the heart. Despite its seeming complexity, this condition is quite common and usually can be completely repaired.

3.19 Congestive Heart Failure

Congestive heart failure (CHF), another disease category, is a syndrome in which the heart is unable to pump the amount of blood required to meet the body's metabolic needs.

Among the many possible causes of CHF are inflammatory cardiac disorders, cardiomyopathy, and congenital heart disease. Congestive heart failure may be predominantly left- or right-sided.

Heart failure affects the kidneys' ability to dispose of sodium and water. The retained water causes edema, particularly in the lower extremities, as seen in this illustration. Fluid can also accumulate in the lungs.

Cardiomegaly is often a compensatory mechanism in persons with CHF, wherein the fibers of the heart muscle stretch to try to increase the force of contractions.

3.20 Heart Transplantation

Treatment of CHF often includes pharmacologic and nutritional components. Cardiac drugs may be given to improve the pumping action of the heart and to promote excretion of fluids. Dietary sodium and fluid intake may be restricted.

If efforts to control CHF with medications and diet fail, heart transplantation, the surgical removal of a donor heart and transfer of the organ to a recipient, may be a treatment option.

3.23 Pathologic Cardiac Conditions

Now to a final grouping of pathologic cardiac conditions: disorders of the coronary arteries and the vascular system. A large number of illnesses fall within this category.

3.24 Atherosclerosis

The most common type of coronary artery disease is caused by atherosclerosis, the formation of fatty deposits along the inner linings of the arteries. Atherosclerosis is a kind of arteriosclerosis, a term that refers to conditions in which there is hardening or thickening of the arterial walls, or loss of their elasticity.

The collection of atherosclerotic deposits in arteries causes them to narrow and become less flexible. Their smooth inner surfaces become rough. Eventually the arteries become occluded, partially or completely blocked, preventing the free flow of blood.

Atherosclerosis affecting the arteries that supply blood to the heart is called coronary artery disease (CAD). CAD is the leading cause of death in the Western world.

3.25 Occluded Artery

Roughening of the vessel lining can result in thrombosis, the abnormal clotting of blood that may block a coronary artery. Arterial blockage, whether by atherosclerosis or thrombosis, causes ischemia, a decrease in the supply of oxygenated blood to a body part, in this case, the heart muscle.

Angiography and Doppler ultrasound studies are useful in the diagnosis of vascular occlusion.

Atherectomy and endarterectomy are surgical procedures for removing atheromas, deposits of fat, from arterial walls.

3.26 Angina Pectoris

Now let's consider some of the possible consequences of insufficient blood supply to the heart. Angina pectoris, often simply referred to as "angina," is a specific type of chest pain that occurs when the heart's demand for oxygen cannot be met because the flow of blood in a coronary artery has been impeded. The illustration demonstrates the location of chest pain during angina.

Mild, transient attacks of angina pectoris are treated with the sublingual administration of nitroglycerine tablets. You will recall that sublingual means under the tongue. This medication acts as a vasodilator, causing the vessel walls to relax and expand, permitting greater blood flow and relieving the pain.

Cardiodynia and cardialgia are terms that are also used to refer to pain in the anterior chest.

3.27 Myocardial Infarction and CPR

Complete interruption of blood flow in a coronary artery causes myocardial infarction (MI), destruction of myocardial tissue, which is also called a heart attack. As you learned in Lesson 2 of this module, blood tests for the cardiac enzymes LDH and CK are used to confirm the diagnosis of myocardial infarction. The terms infarct and infarction refer to localized areas of necrosis (death) in a tissue due to local ischemia from an interruption in the blood supply to the area.

When a heart attack results in cardiac arrest, cardiopulmonary resuscitation (CPR) is the emergency procedure for providing basic life support. Artificial ventilation and external cardiac massage are applied to maintain circulation to the brain until further treatment enables the heartbeat to resume unaided.

Medications in the drug class called beta blockers are often prescribed for patients who have had a heart attack because these drugs reduce the force and speed of the heartbeat and lower blood pressure.

3.28 Percutaneous Transluminal Coronary Angioplasty (PTCA)

Treatment of CAD typically begins with administration of medications to enhance coronary blood flow.

Percutaneous transluminal coronary angioplasty (PTCA) is a nonsurgical intervention for treatment of coronary artery disease. During PTCA, a balloon-tipped catheter and a meshlike tube called a stent are threaded into a coronary artery to dilate the clogged vessel. The stent is designed to prevent closure of the vessel during and after angioplasty.

Another type of nonsurgical treatment for coronary occlusion is laser angioplasty. This procedure causes the destruction of obstructing plaque in an artery, using a tiny laser device that is introduced via catheter in the course of arteriography, or attached to the fiber-optic probe used for angioscopy.

3.29 Coronary Artery Bypass Graft (CABG)

If coronary artery obstruction is too extensive or is unresponsive to medical therapy, a coronary artery bypass graft (CABG) may be performed. In this surgical procedure, a blood vessel is grafted onto one of the coronary arteries to bypass the area of occlusion. A triple bypass is illustrated.

3.30 Vasoconstriction and Vasodilation

Now we'll discuss some conditions that may affect blood vessels other than the coronary arteries.

Vasoconstriction is the narrowing (constriction) of blood vessels. When blood vessels constrict, the flow of blood is restricted or slowed and the blood pressure becomes elevated. Vasoconstriction may be referred to as angiostenosis.

Vasoconstriction may be slight or severe. It can result from disease, or it may be caused temporarily by the response of the nervous system to medications or emotions. Medications that cause vasoconstriction are called vasoconstrictors; they include decongestants and caffeine.

Vasodilation and vasodilatation are terms that refer to the expansion of blood vessels. This increase in the diameter of the vessels increases the volume of blood flow to a part. Extreme vasodilation causes hypotension and shock. Vasodilation may be treated with vasoconstrictors. Vasodilators are medications that cause vasodilation; they are used to treat or prevent vasoconstriction.

3.31 Aneurysms

An aneurysm, indicated in medical terms by the combining form aneurysm/o, is the dilation, or ballooning, of a weakened portion of an arterial wall (Figs. A-C). Although aneurysms of the peripheral arteries may occur, these outpouchings most commonly affect the aorta.

Atherosclerosis is a frequent cause of aortic aneurysms. Aneurysms are often detected by chest x-ray, but electrocardiography, echocardiography, computed tomography, and magnetic resonance imaging may also be used to diagnose and assess the severity of aneurysms.

3.32 Aneurysmectomy

Therapeutic management of aneurysms aims to prevent rupture, and surgery is typically the treatment of choice. Aneurysms in smaller arteries may be treated by clamping off the blood flow to the weakened portion of the vessel. Larger arteries require aneurysmectomy, surgical excision of the aneurysm (as seen in the illustration), often with application of a synthetic graft over the arterial defect.

3.33 Deep Vein Thrombosis

Venous thrombosis, also called phlebothrombosis, is a condition characterized by the presence of a blood clot in a vein. A clot may form in response to injury to the vein, infection, or slowed or halted blood flow—called venous stasis—that may occur following surgery or during prolonged periods of inactivity, or in hematologic disorders in which the blood tends to clot more rapidly than is normal.

As the clot enlarges, the body responds by producing an inflammatory reaction in the area. Venous thrombosis with inflammation is called thrombophlebitis. Symptoms of this condition include tenderness, pain, swelling, warmth, and discoloration of the skin (as seen in the accompanying illustration).

This condition is potentially life-threatening because a portion of the blood clot can break off, forming an embolus, an object that travels through the bloodstream until it lodges in a smaller vessel and blocks it. Often the blocked vessel is the pulmonary artery. Anticoagulant medications, such as heparin, that help to prevent blood from clotting, and thrombolytic agents that dissolve existing clots, are administered to treat venous thrombosis.

3.34 Varicose Veins

Varicose veins are swollen and twisted veins, usually found in the lower extremities. Varicosities occur when the venous valves become damaged and fail to prevent the backward flow and pooling of blood in the legs. The blood then collects in the veins and the veins become distended.

Causes of varicose veins include pregnancy, obesity, heredity, illness, and injury. Conservative treatment consists of leg elevation and the use of elastic stockings; for more severe cases, surgery may be required. Surgical removal of a vein is called a phlebectomy and is commonly referred to as a "vein stripping."

3.35 Hypertension

Hypertension is a major risk factor for vascular disease. It is defined as a sustained elevation of blood pressure above 140/90 mm Hg.

The etiology of hypertension is categorized as either essential or secondary. Essential hypertension, the most frequently occurring kind, has no identifiable cause. However, it is associated with obesity, a sedentary lifestyle, increased sodium intake, smoking, high cholesterol levels, and a family history of high blood pressure. Therapeutic interventions include lifestyle modifications and antihypertensive medication.

Calcium channel blockers are drugs that reduce the myocardial oxygen demand, causing arterial relaxation. These medications are used to treat hypertension as well as angina and congestive heart failure.

3.37 Secondary Hypertension (slide show)

Secondary hypertension has a specific cause that is responsible for the elevated blood pressure. Known causes of hypertension include renal disease, endocrine disorders, and neurologic disorders. Treatment of secondary hypertension may involve medication and/or surgery to address the underlying cause.

Section II The Lymphatic System

1.1 Basic Structure and Function

The lymphatic system is a complex network of vessels, ducts, nodes, and organs that perform many important functions in the body.

The lymphatic system transports proteins and excess tissue fluid that leak from the capillaries, returning them to the venous blood. This process is essential to maintain the fluid balance in the body.
The lymphatic vessels absorb and transport fat from the small intestine to the general circulation.
The lymphatic system also plays an important role in immunity by helping to protect the body from foreign, disease-causing microorganisms.

The combining forms lymphat/o and lymph/o are used to refer to the lymphatic system. Lymph/o also refers to lymph, the fluid transported by the system.

1.2 Lymph

Lymph is a clear, watery liquid that flows through the lymphatic vasculature. It is derived from the interstitial fluid surrounding the body's cells.

Under the microscope, we can see both the liquid portion and the cellular composition of lymph. The liquid part contains water, salts, sugar, proteins, lipids (fats), and metabolic wastes. Lymph also contains a variety of white blood cells. As we learned in the preceding module, these cells play an important part in protecting the body against infection.

1.3 Threaded Case Study: Fred

Laboratory examination of Fred's blood reveals some abnormal findings, including red blood cell irregularities and an elevation in the number of white blood cells. Later in the module, we'll learn more about what these findings mean.

1.4 Lymphatic Capillary

The lymphatic vessels begin in the intercellular spaces of the soft tissues of the body. There, fluid that has filtered out of the blood capillaries flows into small single-layered vessels called lymph capillaries. Networks of lymphatic capillaries are widely distributed throughout the body.

1.5 Lymph Drainage Pathways (animation)

Lymph capillaries merge to form larger tubules known as lymph vessels. Lymph vessels are greater in diameter than the lymph capillaries, and they have thicker walls. Like veins, the lymph vessels have valves to ensure a one-way flow of lymph toward two large ducts in the upper chest. From these ducts, lymph flows into the venous return system and rejoins the cardiovasculature. Thus, while the lymphatic system is distinct from the cardiovascular system, the two are intimately connected.

1.6 Lymph Nodes

Lymph nodes are small oval structures that occur in clusters along the paths of the lymph vessels. The nodes vary in size: some are as tiny as a pinhead; others are as large as a lima bean. Lymph is conveyed via the vessels to the lymph nodes, which act as filters, removing invading microorganisms and other noxious agents. The largest clusters of lymph nodes are found in the neck (cervical), in the armpit (axillary), between the lungs (mediastinal), and in the groin (inguinal).

Assessment of Fred's lymph nodes will be an important part of his physical examination.

About 3 liters of lymph are pumped into the bloodstream during a 24-hour period. Because the lymphatic system does not have a muscular pumping organ comparable to the heart, flow of lymph depends on the movements associated with breathing and on contractions of the skeletal muscles. Consequently, during physical exercise, lymph flow may increase 10- to 15-fold.

1.7 Tonsils, Adenoids

In the next module on the respiratory system, you'll learn more about the adenoids and tonsils. For now, know that these organs, paired masses of lymphatic tissue, also play an important role in defending the body against disease. Located in the throat, the tonsils and adenoids serve as a first line of protection against germs entering the body through the nose and mouth.

The combining forms adenoid/o and tonsill/o are used to designate these structures. The term adenoid derives from aden/o, meaning gland, and -oid, meaning like or resembling.

You know that the suffix -ectomy means surgical removal or excision. Tonsillectomy, therefore, means excision of the tonsils, and adenoidectomy is the term for removal of the pharyngeal tonsils or adenoids. When both procedures are performed at the same time, the combined surgery is called a tonsilloadenoidectomy, which is abbreviated T&A.

1.8 Thymus

The thymus, indicated in medical terms by the combining form thym/o, lies in the mediastinum, between the lungs, extending into the lower neck.

Unlike the tonsils and adenoids, the thymus is a single organ, consisting of two lobes that contain lymphoid cells.

The thymus appears to perform its most important work during the prenatal period and early childhood when its size, relative to the rest of the body, is largest. The thymus is essential to the development of the body's immune system.

1.9 Threaded Case Study: The Spleen

The spleen is an organ with an ovoid shape that is located in the left upper quadrant of the abdominal cavity, between the stomach and the diaphragm. Although it is seldom essential to life, it performs a variety of important functions.

As blood flows through the spleen, harmful micro-organisms are filtered out and old red blood cells and platelets are destroyed. White blood cells are produced and activated within the spleen. The spleen, which is the largest lymphatic organ in the body, also acts as a reservoir for blood storage. The combining form splen/o is used in terms that refer to the spleen.

Fred's spleen appears to be slightly enlarged. The doctor will integrate this information with other findings in arriving at a diagnosis of Fred's condition.

2.1 Disorders of the Lymphatic System

In the previous lesson, we looked at the organs and functions of the lymphatic system. In this lesson, we'll consider some disorders of the lymphatic system.

You may recall that the relationship between the spread of cancer and the lymphatic system was first mentioned in Module 3. Cancer cells can travel through lymph vessels; they may be filtered from the lymph in a lymph node and begin to grow a new cancer there, or they may be transported to other sites in the body via the network of lymphatic vessels.

The spread of cancer to a site remote from the initial tumor is called metastasis, and metastatic means pertaining to metastasis. A metastatic tumor is a malignant growth that occurs secondary to the original, or primary, tumor and is not directly connected to it.

2.2 Inflammatory Conditions of the Lymphatic System

Many of the terms used to indicate inflammatory conditions of the lymphatic system are built from word parts. Typically these terms are constructed by appending the suffix -itis to word roots that give us specific information about the affected structure. One such term is lymphangitis, an inflammation of one or more lymphatic vessels (Fig. A).

The definitions of the word parts in the term lymphadenitis (Fig. B) tell us that the inflammation affects the glands of the lymphatic system. A more general term, lymphadenopathy, is used to refer to any disease characterized by enlargement of the lymph nodes or vessels.

2.3 Obstruction of Lymph Flow

You'll recall in the previous lesson that we pointed out an important difference between the cardiovascular and lymphatic systems: the lymphatic system does not have a muscular pumping organ comparable to the heart. Instead, the flow of lymph depends on movements associated with breathing and with contraction of the skeletal muscles.

Inflammation, obstruction, or removal of lymph channels can stop the flow of lymph, a condition known as lymphostasis. As lymph accumulates within the tissues, lymphedema, or swelling, occurs.

Disorders of the lymphatic vessels are diagnosed with the use of lymphangiography, a type of radiographic imaging.

2.4 Threaded Case Study: Fred

Physical examination revealed enlargement of Fred's cervical and axillary lymph nodes. Lymphangiography, radiographic studies, computed tomography scans, and a lymph node biopsy were performed to provide a definitive diagnosis of Fred's condition. We'll soon learn more about what the doctor believes is responsible for Fred's health complaints.

2.5 Splenomegaly

As an organ of the lymphatic system, the spleen plays a vital role in providing the body with immunity from disease. It is also a site for blood cell production and blood storage. Enlargement of the spleen, splenomegaly, is associated with a variety of infectious processes and blood disorders.

2.6 Thymoma

A thymoma, as you can tell from the word parts, is a tumor of the thymus gland, an organ of the lymphatic system.

Thymomas are slow-growing lesions and usually behave in a benign fashion. A subgroup of these tumors has an aggressive nature and is called invasive thymoma.

A thymoma may result from an immune system disorder; it may also be associated with other types of illnesses, particularly myasthenia gravis. Myasthenia gravis is a disorder of neuromuscular transmission associated with immunological abnormality. It causes fatigue, muscle weakness, and a variety of other symptoms.

Surgery is the preferred method of treating thymomas. Excision of the thymus is called thymectomy.

2.7 Lymphomas

Lymphomas, the fifth most common type of cancer in the United States, are malignant neoplasms of the lymph nodes and lymph tissues. The two major types of lymphoma are Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL).

The origin of Hodgkin 's disease is unknown, but it is associated in the majority of cases with a few specific viruses, particularly the Epstein-Barr virus that causes mononucleosis and the measles virus. It is characterized by progressive enlargement of lymphoid tissue.

2.8 Non-Hodgkin's Lymphoma

The symptoms and course of both types of lymphoma are very similar, but the lymphatic tissue in Hodgkin's disease contains specific cells—Reed-Sternberg cells—that are not found in any other cancerous lymphomas or cancers. These cells distinguish Hodgkin's disease from non-Hodgkin's lymphomas.

Those with early stages of lymphoma are treated with high-dose radiation; advanced disease may be treated with intensive chemotherapy alone or in combination with radiation. A high rate of cure is obtained with these treatment methods.

2.9 Threaded Case Study: Fred

Fred's physician has concluded that his symptoms—lymphadenopathy, splenomegaly, occasional arrhythmia, fatigue, weight loss, anemia, and an elevated white blood cell count—are manifestations of Hodgkin's lymphoma. Fred and his doctor have discussed treatment options and plan to manage this condition with chemotherapy and radiation to the involved sites. A team of medical providers will help Fred address the physical and psychosocial implications of his diagnosis, and he is encouraged to learn of the favorable prognosis for many of those with Hodgkin's disease.

Word Parts

If you've studied the combining forms, prefixes, and suffixes in your text, you're now ready for the additional practice you'll receive with word parts in this module. Check your glossary for definitions of all the word parts used in the following exercises. To review the construction of medical terms using prefixes, combining forms, and suffixes, return to earlier modules in this series. Click Next to continue.