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The Human Body
AMS SALES TRAINING
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THE HUMAN BODY OVERVIEW
Understanding the basic functioning of the human body is a
critical prerequisite to understanding the medical products you
sell and the procedures in which they are used.
Your customers go through years of training on the topics
introduced in this course. Fortunately, as a sales rep, you don’t
need such in-depth knowledge. Still, the introduction you’ll
get in the course will prove very valuable. Your investment in
learning about body systems, organs, and functions will make
you a more informed and more trusted partner for your clinical
customers.
AFTER COMPLETING THIS COURSE YOU WILL BE ABLE TO:
»» Describe the relationship between anatomy and physiology.
»» Understand basic medical terminology using word roots, prefixes, and
suffixes.
»» Understand the organs and functions of each body system including
the integumentary (skin), skeletal, muscular, nervous, endocrine,
circulatory, respiratory, digestive, urinary, and reproductive systems.
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Anatomy and physiology
Anatomy is the study of the structure and shape of the body and its parts, and their relationship
to one another. Gross anatomy (large body structures) can be observed with the naked eye, while
microscopic anatomy (small structures within the body) requires a magnifying instrument.
Physiology is the study of how the body and its parts work or function. For example, kidney
physiology is the study of how the kidney filters the blood and produces urine.
It is difficult to separate anatomy and physiology because they are always related. The different
parts of the body are arranged to form a well-organized unit, and each part works to help the body
function as a whole. Additionally, the structure of each part determines its function.
To illustrate this concept, let’s describe the “anatomy” and “physiology” of an automobile. The
various parts of a car—its “anatomy”—include such structures as the wheels, the engine, the
headlights, and the seats. Each of these parts works together to assist the car in functioning as a
whole unit—a motor vehicle. That functioning is the car’s “physiology”. The structure of each car
part relates to its function. For example, the wheels are round and therefore provide the function
of smooth, rolling movement.
In the human body also, structure always relates to function. For example, the lungs are
anatomically structured to provide gas exchange for the function of breathing. The heart, however,
is anatomically structured to provide pumping action for the function of blood circulation. So,
anatomy and physiology are always related and work together closely to enable the human body
to function as a whole unit.
The body contains several cavities. These cavities evolve in the early days of the developing
embryo and protect the organs inside them. In the most general terms, the cavities exist within
either the dorsal (toward the back) or ventral (toward the front) cavities as shown in the figure on
the following page.
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The dorsal cavities consist of the cranial cavity and the spinal cavity which together house the
central nervous system. The cranial cavity inside the head holds the brain. The spinal cavity
running down the back holds the spinal cord.
The ventral cavity includes the thoracic cavity of the chest and the abdominopelvic cavity directly
beneath it. Fibrous tissue walls separate the three components of the thoracic cavity. Each lung is
enclosed in its own sac. The heart, trachea, right and left bronchi, esophagus, thymus gland, certain
blood vessels, the thoracic duct and other lymphatic vessels, certain lymph nodes, and some nerves
are enclosed in the center of the chest. The abdominopelvic cavity encompasses the rest of the
organs of the trunk.
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Introduction to medical terminology
You will be introduced to medical terms in this course and others. Some knowledge of how they
are derived and constructed will help make them more meaningful to you.
Most medical terms consist of combinations of Greek or Latin words. Often a basic word identifies
a structure while other syllables that precede or follow the stem word specify what happens to it.
Thus, medical terminology follows a logical construction process. If you learn that process and
commit common components to memory, you can deduce the meaning of many terms by simply
breaking them down into their components.
Word roots
The essential element (or elements) of a medical term is known as the word root. It is usually
the part that identifies the structure being referred to. It serves as the foundation for constructing
names of procedures, diseases, conditions, anatomical descriptions, locations, and instruments.
Some word roots are familiar to most of us:
•
•
•
•
Cardi- for heart
Gastr- for stomach
Derm- for skin
Vertebr- for vertebrae
Others, like nephr- for kidney, will require some effort to remember.
To make the word root pronounceable when combined with another word root or an ending, called
a suffix, a vowel is usually added. Most often that vowel is an o.
Compound words link two or more word roots to create a single word. Electrocardio-graph, for
example, combines two roots and the suffix, -graph, to name a device that measures the electrical
potentials across heart muscle.
Suffixes
New words are often formed by adding syllables to the end of the word root. The ending syllables
or suffixes often describe symptoms, something done to or happening to a structure. They may
convert the word root to:
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•
•
•
•
A noun with endings such as –ism, -ia, -graph
An adjective that means pertaining to, with endings like –al, -ical, -ary
A plural, with, for example, -ina, -aces, -mata
A smaller version, with -ole, -icle, -ule
Prefixes
Syllables located in front of a word root modify it by designating position, color, direction, and so
forth. A few examples:
• Ab-: opposite of or removed from as in abduction
• Ad-: motion toward as in adduction
• Hypo-: below, at a lower point, abnormally low, deficient as in hypogastric
For your ongoing reference, the tables on pages 54-59 present a summary of word roots and
combining forms, suffixes, and prefixes.
Organ systems structure and function
Integumentary system
Structure = skin
Function = provide protection, communicate with the outside, and impart the unique appearance
that lets others recognize us
Skeletal system
Structure = bones, cartilage, tendons and joints
Function = support the body and provides framework for muscles; provide protection
Muscular system
Structure = muscles
Function = contract and shorten in order to provide movement
Nervous system
Structure = brain, spinal cord, nerves, and sensory receptors
Function = receive data, analyze it, and react to it
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Endocrine system
Structure = glands including pituitary, thyroid, parathyroid, adrenal, thymus, pancreas, pineal,
ovaries (female), testes (male)
Function = secrete hormones for the purpose of regulating other organ systems
Circulatory system
Structure = heart, blood vessels and blood
Function = transport and deliver fluid throughout the body
Respiratory system
Structure = nasal passages, pharynx, larynx, trachea, bronchi and lungs
Function = supply the body with oxygen and remove carbon dioxide
Digestive system
Structure = mouth, esophagus, stomach, small and large intestines, and rectum
Function = break down food and deliver it to the blood for dispersion throughout the body; remove
solid waste
Urinary system (also known as the excretory system)
Structure = kidneys, ureters, bladders and urethra
Function = remove liquid wastes while maintaining the body’s water and chemical balance
Reproductive system
Structure (male) = testes, scrotum, penis, accessory glands and duct system
Structure (female) = ovaries, fallopian tubes, uterus and vagina
Function = produce offspring
Integumentary system
The integument is the skin, the largest organ of the body. The skin contains a number of structures
such as hair, nails, and surface glands. It separates us from our environment, provides protection,
communicates with the outside, and imparts the unique appearance that lets others recognize us.
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Structures and functions
Contrary to common belief, we humans are rather thick-skinned. With four or five layers of
epidermis and two layers of dermis, skin has the structure of plywood. And yet, skin tends to
be elastic. It also repairs itself constantly, with minor injuries healing rapidly. The outer layers
perpetually shed and are replaced by new cells. Along with epithelial tissue, skin is composed of
numerous structures that ceaselessly monitor and respond to the environment as shown below.
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• Blood vessels in the skin bring blood from the warm interior to surface layers.
• Hair, a nonliving filament made of a tough protein called keratin, serves both a sensory
and a protective function. When a particle of dust contacts an eyelash, for instance, the eye
automatically closes.
• Hair follicles, tiny onion-shaped organs imbedded in the dermis, are supplied withsensory
nerves and a smooth muscle that contracts to pull the hair upright when a person experiences
“goose bumps.”
• Skin glands are of three types.
◦◦ Sebaceous glands, usually attached to hair follicles, empty an oily emollient into the
canal from which the hair emerges.
◦◦ Apocrine glands are sweat glands located in several areas—the most recognizedbeing
the armpits, where the fluid secreted causes a foul odor when it comes in contact with
bacteria.
◦◦ Eccrine glands, well represented in the armpits and throughout the body, pour out water
which evaporates and cools the surface and. subsequently, the blood. These glands are
commonly referred to as exocrine glands implying that their secretions are delivered
to the body surface by ducts. Technically, apocrine glands are also a specific type of
exocrine gland.
• Nails allow for manipulating tiny objects, protect tender finger and toe tips, and allow
enhanced sensation in the tips through pressure. Made of dead cells heavily fortified with
keratin, the nails grow from a root of living tissue, taking three to four months to complete
the journey from root to tip.
The skeletal system
A human skeleton is composed of 206 bones, arranged in such a way as to permit bodies to run,
walk, and balance themselves. Bones are strong and hard enough to provide support for the body,
in the same way that steel girders support buildings. Yet, bones are pliable and flexible enough to
permit muscle contractions for the purpose of movement. A diagram of the skeletal system follows
on the next page.
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Functions
In addition to making up the frame supporting a body, bones of the human body have four primary
functions:
• To provide a hard internal support for some body organs and to protect other organs by
enclosing them
• To serve as levers for the muscles to pull on to cause movement at joints
• To store calcium, fats, and other substances for the body
• To hold red marrow and be the production site of blood cells
Let’s look at these functions in more detail. Bones protect the organs beneath them. For example,
the bony thorax, or rib cage, protects organs such as the heart and lungs. Bones have various
anatomical landmarks called projections and depressions. These landmarks give rise to a bone’s
“scarred” surface appearance and indicate where muscles attach(ed) and where blood vessels and
nerves pass(ed). So, it can be said that bones enjoy a very close relationship with blood vessels,
nerves and muscles.
The skeletal system also acts as a “storage bin” for lipids (fats) and calcium. In order for the
nervous system to transmit messages, for the muscles to contract, and for the blood to clot, calcium
must be available in the blood at all times. Because calcium is stored in bone, the blood can easily
extract it as necessary. Last, but not least, the red marrow cavities of the bone provide a site for
blood cell formation, also known as hemopoiesis.
Structure
The human skeleton is composed of two very strong tissues: cartilage, which is primarily connective
tissue, and bone.
In the embryonic stage, the skeleton is mostly cartilage. As the body develops, however, into a
young child, the skeleton primarily consists of bone, with cartilage present only in areas such as
the bridge of the nose, parts of the ribs and the joints.
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The skeleton is divided into two parts: the axial skeleton, which includes bones that form the
longitudinal (lengthwise) axis of the body, and the appendicular skeleton, which forms the bones
of the limbs (arms and legs) and the girdles (pelvis and shoulder). The skeletal system also includes
joints, which hold bones together and allow movement to occur, and ligaments, which are cords
that bind the bones at joints.
The axial skeleton comprises the skull (formed by cranial and facial bones), the vertebrae or spinal
column and the bony thorax (formed by the sternum and ribs). The appendicular skeleton consists
of the shoulder girdle, the bones of the upper limbs, the pelvic girdle, and the bones of the lower
limbs.
Bones are classified into four groups depending on their shape and composition. These groups
are long, short, flat and irregular. Long bones are found in the limbs, except the wrist and ankle,
where short bones are located. The skull and sternum (breastbone) are made up of flat bones, while
irregular bones include the bones of the spinal column and all bones that do not fit in any other
category.
Bone is one of the hardest materials in the body, is relatively light in weight, and has a remarkable
ability to resist tension and other forces acting on it. So why do bones break?
Bone fractures
Despite their incredible strength and durability, bones are susceptible to fractures, or breaks,
throughout life. When we are young, we are susceptible to fractures due to trauma from falls or
sports activities that compress or twist the bone. In our old age, when bone is lost faster than it is
replaced due to the aging process, fractures occur due to bone thinning and general loss of strength.
A fracture is treated by realigning the ends of the broken bone. This process is called reduction and
may be either closed reduction or open reduction. In closed reduction, the physician manipulates the
broken bone back together with his or her hands. In open reduction, the physician performs surgery
and the bone ends are held together with pins or wires. Alter closed reduction, the physician may
or may not immobilize the area by using a cast or traction. After open reduction, however, a cast or
traction is almost always used to ensure that the area remains immobilized. The healing time of a
simple fracture is usually six to eight weeks, except in the elderly where it may take much longer.
General and family practitioners (GPs and FPs), and particularly orthopedic surgeons (bone
specialists) often treat fractures.
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The muscular system
The main function of muscles is to provide body movement. Muscles accomplish this by contracting
and shortening. This unique characteristic sets the muscular system apart from any other tissue in
the human body. In fact, the muscular system is responsible for all body movement, whether the
movement is voluntary (a result of a command we consciously give to a certain muscle or group of
muscles) or involuntary (a result of our brain telling a muscle to contract without our being aware
of it).
Types of muscle
There are three types of muscle tissue in bodies: skeletal, smooth, and cardiac. Each of these three
muscle types has a structure and function well suited for its job in the body.
Skeletal muscle is known as voluntary muscle because its contraction is subject to our command.
It is also known as striated muscle because it is striped. There are over 600 skeletal muscles in the
body accounting for approximately 40 percent of body weight. It is because of the skeletal muscles
that we are able to run, walk, swim or play tennis. The skeletal muscles are attached to the bones
of the body much like cables are attached to an elevator. When the muscles or the cables contract,
the body or the elevator moves. But the skeletal muscles do not only cause large and obvious
movements. They also enable us to accomplish much more subtle movements like smiling or
frowning by contracting our facial movements which reflect our moods.
Smooth muscle is involuntary with regard to contractibility which means that we cannot consciously
control it. Smooth muscle can be found in the walls of the blood vessels, the intestine, bladder and
various other internal organs. One of the main functions of smooth muscle is to propel or move
substances along a clearly defined tract or pathway. For example, smooth muscle helps move food
down the esophagus (the tube leading from the throat to the stomach) and through the digestive
system.
Cardiac muscle is found only one place in the body—the heart. Cardiac muscle is involuntary with
regard to its contractibility and cannot be controlled by most people.
Cardiac muscle is highly specialized to perform the pumping action of the heart which propels
blood throughout the body to all tissues.
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Muscle activity
To contract, skeletal muscles must be stimulated in a process which involves nerves, neurotransmitters
(chemicals released at the site of contraction), and electrical impulses that result in a change in the
body’s ions (positive and negative charges). While the process of muscle contraction requires the
“work” of several different body components, the time required for a muscle to contract is only a
few thousandths of a second.
There are two types of muscle contractions: isotonic and isometric. Isotonic contractions are more
familiar to us because they refer to such actions as bending the knee, rotating the arm, or winking
the eye. Isotonic contractions happen when the muscle shortens and movement results. Isometric
contractions, on the other hand, refer to contractions in which the muscle does not shorten but
rather increases its tension as if it were pushing against an immovable object.
Types of body movements
Every muscle is attached to bone or other connective tissue structures at two points. The origin
is the part of the muscle that is attached to the immovable or less-movable bone, and the insertion
is the part attached to movable bone. When the muscle contracts, the insertion moves toward the
origin. The muscle attachments are shown on the following page.
There are several terms with which you should be familiar regarding muscle movement:
• Flexion: bringing two bones closer together, like when you bend your elbow or knee
• Extension: the opposite of flexion, like when you straighten your elbow or knee
• Abduction: moving a limb (arm or leg) away from the midline of the body
• Adduction: the opposite of abduction: moving a limb toward the midline of the body
• Rotation: the movement of a bone around its longitudinal axis; common for ball-and-socket
joints like the one found in the hip
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PROGRESS CHECK
1. Which of the following is the study of how the body and its parts work or function?
A) Anatomy
B) Gross anatomy
C) Physiology
D) Nephrology
2. Divide the following words for their prefixes, word roots, and suffixes and indicate their
meaning. Refer to the information on pages 54-59 in the back of the course if necessary.
Mesoderm: ______________________________________________________________
Pericarditis: _____________________________________________________________
Colostomy: ______________________________________________________________
Hepatocarcinoma: ________________________________________________________
Hydrocephalus: __________________________________________________________
Subcartilaginous: _________________________________________________________
Transfuse: _______________________________________________________________
3. What is the major organ of the integumentary system?
________________________________________________________________________
4. Name the four primary functions of bone:
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
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PROGRESS CHECK
continued
5. Which word refers to blood cell formation?
A) Comminutation
B) Hemopoiesis
C) Homeostasis
D) Hyporentation
6. What is the primary function of the muscular system?
________________________________________________________________________
7. Name two types of muscle contraction.
________________________________________________________________________
________________________________________________________________________
8. Which word means bringing two bones closer together?
A) Flexion
B) Extension
C) Abduction
D) Adduction
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PROGRESS CHECK ANSWERS
1. C) Physiology
2. Mesoderm: middle/layer of skin
Pericarditis: near/heart/inflammation
Colostomy: colon/surgical opening
Hepatocarcinoma: liver/cancer/swelling
Hydrocephalus: water/head/(noun ending)
Subcartilaginous: below/cartilage/pertaining to
Transfuse: across/pour
3. The skin
4. The four primary bone functions are:
•
•
•
•
to provide a hard internal support for the body and its organs
to serve as levers for the muscles to pull on to cause movement at joints
to store calcium, fats, and other substances for the body
to act as the location for red marrow, the site of blood cell production
5. B) Hemopoiesis
6. To provide movement.
7. Isotonic and isometric
8. A) Flexion
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The nervous system
The nervous system is the master controlling and communicating system of the body, acting as
the body’s mainframe computer. A computer takes the data supplied to it by the input operator,
analyzes it according to the program it has been “taught” and makes a decision or supplies an
answer based on that program. Like a mainframe computer, the nervous system receives data
from the external environment and the body’s own internal environment, analyzes it according to
“lessons learned” through experience or the body’s own internal programs, and reacts accordingly.
Lessons learned include such things as not putting your hand on a hot stove. Electrical impulses
serve as the nervous system’s signaling device, or its means of communicating with body cells.
These electrical impulses are rapid, specific, and cause immediate, almost simultaneous responses.
We are what our brain has experienced over time, and therefore, it’s easy to understand why
damage to the brain causes such devastating effects. Erasing sensory input from the past could
render us unable to walk, talk, or communicate in any manner. The nervous system does not act
alone in regulating body functions (the endocrine system does this as well); however, it plays a
vital role.
Divisions of the nervous system
The nervous system is divisible anatomically (by structure) or functionally (by activity).
Anatomically, the nervous system has two primary subdivisions: the central nervous system (CNS)
and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord while
the PNS consists of nervous system structures outside the CNS. The PNS carries impulses or
information to and from the brain via cranial nerves, and to and from the spinal cord via the spinal
nerves. These nerves act as communication lines linking parts of the body in the same way that the
Internet links parts of the world.
The structures of the nervous system can also be divided by function, or in terms of motor activities.
This classification also has two subdivisions. The somatic nervous system allows us to consciously,
or voluntarily, control our skeletal muscles. The autonomic nervous system regulates activities that
are automatic, or involuntary, such as the activation of smooth and cardiac muscles. While we
have divided the nervous system into many parts in order to facilitate learning, it is important to
remember that the nervous system acts as a coordinated unit, both structurally and functionally.
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Nervous tissue
Nervous tissue is made up of two types of cells—neuroglia and neurons. The neuroglia, which
literally means nerve glue, include many types of cells that generally support and protect the
neurons in the CNS. Neuroglia are not able to transmit nerve impulses.
Conversely, neurons are highly specialized to conduct or transmit messages from one part of
the body to another, and they do not have the ability to divide or reproduce. Neurons that carry
impulses to the CNS from various parts of the body are known as afferent or sensory neurons, and
neurons that carry impulses from the CNS to the parts of the body are known as efferent or motor
neurons. Neurons connecting motor and sensory neurons via pathways are known as association
neurons. Neurons “fire” or transmit impulses through an electrochemical event. In other words,
impulses are transmitted as a result of electrical and chemical changes within the neuron. For
example, when you place your hand on a hot stove, your afferent (sensory) neurons carry the
message that the stove is hot to your brain (CNS). The association neurons carry the message from
the afferent neurons to the efferent (motor) neurons, which in turn, send the message back to your
hand to remove it from the heat. Types of neurons and the nervous system are illustrated on the
following pages.
Nervous tissue is very soft and delicate. It has the consistency of slightly dried-out oatmeal, and
the fragile neurons can be injured by even the slightest pressure. That’s why nature has tried to
protect the brain and spinal cord by enclosing them within bone (the skull and vertebral column or
backbone), membranes (called the meninges) and a watery cushion (the cerebrospinal fluid).
Since the nervous system starts forming early in embryonic development, the effects of a maternal
disease during pregnancy can be devastating (lack of oxygen could mean nerve death or cerebral
palsy, a motor disorder; or maternal measles can cause deafness). No neurons are made after birth
but the nervous system continues to grow during childhood.
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The endocrine system
As you learned in the previous section, the nervous system is the major controlling and
communicating system of the body. However, as discussed, it does not accomplish this alone.
The other body system that plays a major role in controlling and communicating is the endocrine
system. Along with the nervous system, it helps to coordinate and direct the activity of the body’s
cells. Unlike the nervous system, however, the endocrine system works more slowly and uses
chemical messengers, or hormones, rather than fast-acting nerve impulses to transmit its messages.
The endocrine system releases hormones into the blood to be transported throughout the body.
Unlike other systems in the body, the endocrine system is located in bits and pieces all over the
body, lacking “anatomic continuity.” While the total weight of the endocrine glands is less than
one-half pound, they are extremely impressive when their important functions are considered. An
overview of the endocrine system is on the following page.
Overall function
The endocrine system is critical to homeostasis, a state of body equilibrium or internal stability.
The incredible power of the endocrine glands lies within the hormones they produce and secrete.
Hormones arouse the body’s cells by stimulating changes in the body’s metabolism. These
metabolic changes lead to growth and development as well as functional stability of many body
systems. Since the endocrine system plays such an important role in the body’s overall functioning,
even a slight change in hormonal balance can have a profound effect.
As mentioned earlier, hormones are circulated throughout the body via the blood. However, a
given hormone affects the activity of only a specific organ or organs, which are often referred to as
the target organs for that hormone. These target organs or tissues have specific receptors to which
the hormone attaches. It is only after this attachment takes place that the hormone can influence
the inner workings of the cell.
The pituitary gland is approximately the size of a grape and is located in the central portion of the
brain. It has two functional areas, the anterior pituitary and the posterior pituitary. The posterior
pituitary acts as a storage area for hormones made by other endocrine glands. The anterior pituitary,
which controls many other endocrine glands, is often called the “master endocrine gland.” The
anterior pituitary secretes such hormones as the growth hormone, which affects the growth of
skeletal muscles and the long bones of the body. The growth hormone plays an important role in
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determining final body size. Too little of this hormone can result in dwarfism, and too much can
result in giantism. The anterior pituitary gland is also responsible for regulating the hormonal
activity of the gonads (testes and ovaries) through the secretion of gonadotropic hormones.
The thyroid gland is located at the base of the neck, just below the Adam’s apple, where it can
easily be palpated (felt) during physical examination. The thyroid makes thyroxine, which controls
the rate at which the body produces energy from various food substances. Thyroxine is dependent
on iodine. Too little iodine in a person’s diet can result in goiters (enlarged thyroid). If too little
thyroxine is secreted in infancy, dwarfism can result. In addition, fatigue, low body temperature,
and obesity can all be the results of too little thyroxine. Too much thyroxine can result in a high
metabolic rate, intolerance of heat, rapid heart rate, and weight loss. In some cases, a person’s eyes
may even begin to bulge.
The parathyroid glands are found on the posterior surface of the thyroid gland. These glands
secrete hormones that regulate the amount of calcium in the blood.
The adrenal glands are bean-shaped and sit on top of the kidneys. The adrenal glands produce
corticosteroids (steroid hormones) that are responsible for regulating the mineral (salt) content of
the blood, and for promoting normal cell metabolism.
The gonads consist of the ovaries in the female and the testes in the male. The ovaries secrete
estrogen and progesterone and the testes secrete testosterone. We will discuss each of these
hormones in greater detail, in the section on reproduction.
The circulatory system
The circulatory system functions as the body’s transportation system. It uses hollow blood vessels
for delivery routes and blood as the transport vehicle. Oxygen, nutrients, cell wastes, and many
other substances are transported throughout the body via the blood which is forced through the
blood vessels by the beating heart.
The circulatory system has two major subdivisions—the cardiovascular system and the lymphatic
system. This section will concentrate on the cardiovascular system and only touch on the lymphatic
system. The cardiovascular system comprises the heart and the blood vessels.
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The heart
The heart is a cone-shaped organ about the size of your fist. It weighs less than a pound and is
located within the bony thorax (chest). The more pointed part of the heart, its apex, rests on the
diaphragm (the muscle separating the chest cavity from the abdominal cavity), which is precisely
where the physician places a stethoscope to listen to your heartbeat during a physical exam. The
heart is enclosed in a membrane called the pericardium, which produces a slippery lubricating fluid
that allows the heart to move (beat) in a frictionless environment. The heart walls are composed of
the thick cardiac muscle known as the myocardium. When someone has a myocardial infarction,
more commonly known as a heart attack, this is the muscle impacted.
The heart is divided into four hollow chambers—two atria and two ventricles. The atria are
receiving chambers into which the blood flows from the veins of the body. The ventricles are the
discharging chambers since they have the major responsibility of forcing blood out of the heart
into the arteries. The heart functions as a pump. The right side receives oxygen-poor blood from
the venous system (veins), and pumps it through the pulmonary arteries to the lungs where it
unloads carbon dioxide and picks up oxygen. The blood then returns to the left side of the heart via
the pulmonary veins. This route—from the right side of the heart to the lungs and back to the left
side of the heart is called pulmonary circulation. The flow of blood from the left side of the heart
through the body tissues and back to the right side of the heart is called systemic circulation. This
route from the heart to the body tissues and organs supplies needed oxygen to all parts of the body.
The heart is equipped with four valves allowing blood to flow through the heart chambers in only
one direction, so that oxygen-poor blood in the atria is not mixed with oxygen-rich blood in the
ventricles. Because the heart is made up of myocardial tissue, it also needs nourishment from
the blood’s oxygen. Coronary arteries provide this. If the myocardium does not receive enough
oxygen, for whatever reason, angina pectoris (crushing chest pain) results, which is often a heart
attack warning sign. The components of the heart, as well as the circulatory route, are noted in the
following illustrations.
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Cardiac cycle
In a healthy heart, the atria contract simultaneously. As they begin to relax, contraction of the
ventricles begins. (Systole and diastole are terms for this contraction and relaxation, respectively.)
The term cardiac cycle is used to refer to one complete heart beat during which both atria and
ventricles contract and relax. The average heart beats 72 times per minute and the normal cardiac
cycle is about 0.8 seconds. The heart has its own electrical conduction system consisting of nerves
governed by the autonomic nervous system and a nodal system that is built into the heart tissue
itself.
These two systems work together to keep the heart in sync, beating properly. However, sometimes
problems occur. Tachycardia refers to an abnormally rapid heart rate over 100 beats/minute and
bradycardia refers to an abnormally slow heart rate less than 60 beats/minute. As you know, heart
rate can be influenced by many things such as fright or exertion.
Blood vessels
As noted earlier, blood vessels form the closed transport system through which the blood flows.
As the heart beats, blood is propelled in the following way: from the heart to the large arteries
(aorta), to the average-size arteries, to the smaller arteries (arterioles), and finally to the capillary
beds which are located in the tissues. After the tissues have extracted their needed oxygen, the
blood flows into the smaller veins (venules), to the average-size veins, and finally into the large
veins (superior and inferior vena cava) which return the oxygen-depleted blood to the heart for
rejuvenation.
Blood pressure
Blood pressure is the pressure the blood exerts against the inner walls of the blood vessels, and it is
the force that keeps the blood continuously circulating even between heartbeats. It is the elasticity
of the vessels that allows them to expand to let the blood flow through and then recoil or contract in
order to keep pushing and moving it along. Because the heart alternately contracts and relaxes, the
on and off flow of blood into the arteries causes the blood pressure to rise and fall during each beat.
This allows for two arterial blood pressure measurements to be made: systolic pressure, which is
the pressure in the arteries at the peak of ventricular contraction, and diastolic pressure, which is
the pressure when the ventricles are relaxing. As is the case with heart rate, blood pressure can be
affected by a variety of things including diet, medication, and exercise.
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The Human Body 29
Lymphatic system
The lymphatic system is a pumpless system consisting of lymphatic vessels and lymph nodes. As
you’ve just learned, the cardiovascular system is a high-pressure system that forces blood into
circulation. Because of this, it tends to be a little “leaky.” This is precisely why the lymphatic
system plays such an important role.
The function of the lymphatic vessels is to pick up this excess tissue fluid (lymph) and return it to
the blood stream. In addition, lymph nodes help protect the body by removing any foreign material
such as bacteria and tumor cells from the lymphatic stream before it is returned to the blood stream.
The respiratory system
A continuous supply of oxygen is required for the body to carry out its vital processes. As the cells
of the body use oxygen, they give off carbon dioxide (a waste product the body must get rid of)
through a process called internal respiration (or cellular respiration). As you know from reviewing
previous sections in this course, the circulatory system plays a role in this process by supplying
the blood that carries the oxygen to the cells and carbon dioxide from the cells. In addition to
the circulatory system, the respiratory system plays a major role in this process. The respiratory
system organs are responsible for the gas exchanges that occur between the blood and the external
environment through a process called external respiration.
Anatomy of the respiratory system
The organs of the respiratory system include the nasal cavities, pharynx, larynx, trachea, bronchi
(and their smaller branches) and the lungs that contain the alveoli or air sacs. With the exception
of the alveoli, which is where the actual gas exchange takes place, the organs of the respiratory
system simply act as passageways to bring air into and out of the lungs. Let’s look at each of
these organs in more detail. As you read the following text, identify the structures on the two
illustrations that follow.
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The Human Body 31
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The nose is the only externally visible part of the respiratory system. During breathing, the air
enters through the nostrils. The nose serves to warm up the air prior to entering the lungs as well
as to trap dust particles and other foreign substances in its moist membranes. The air then passes
into the pharynx, a muscular passageway about five inches long that is commonly referred to as
the throat. The pharynx is a common passageway for both air and food. The pharynx is divided
into several different sections, one of which is the nasopharynx. The eustachian tubes (located in
the middle ear) drain into the nasopharynx. From the pharynx, the air passes over the larynx, or
voicebox, which is located below the pharynx. As you may know, the larynx houses the vocal folds
or vocal cords which vibrate with expelled air, enabling us to speak.
After the air passes by the larynx, it enters the trachea, or windpipe, which is a little over four
inches in length. Since the trachea is the only way air can get into the lungs, it is vital that it remain
open at all times. When the trachea becomes blocked due to a particle of food or other substance,
it is sometimes necessary to perform a tracheotomy, an emergency surgical procedure to open up
this passageway. The trachea splits into two branches known as the right and left primary bronchi
upon entrance into the lungs. By the time the air reaches this point in the respiratory tract, it has
been thoroughly warmed and filtered.
The paired lungs occupy all of the chest cavity except that which is occupied by the heart. Each
lung is divided into lobes—the left lung has two lobes while the right lung has three. The surface
of each lung is covered with pleura, which allows the lungs to glide smoothly over the chest wall
during breathing.
The lungs are mostly air spaces consisting of very small branches of the bronchi called brochioles.
The bronchioles lead to and terminate in the very important alveoli, or air sacs, where gas exchange
takes place. Through simple diffusion, oxygen passes from the alveolar air into the capillary blood,
and carbon dioxide passes from the capillary blood into the alveolar air where it is expelled through
a process called expiration. It has been estimated that the total gas exchange surface provided by
the alveolar walls of a healthy human being is about 600 square feet.
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The Human Body 33
Physiology of the respiratory system
The main purpose of respiration is to supply the body with oxygen and get rid of carbon dioxide.
To do this, the following three processes must take place:
• Air must move into and out of the lungs, a process called ventilation.
• The exchange of gases between the blood and the alveoli must occur, a process called
external respiration.
• Gas exchanges must be made between the blood and the body tissues, a process called
internal respiration.
Ventilation has two phases: inspiration, where air is brought into the lungs, and expiration, where
air is expelled from the lungs. This exchange is accomplished through the action of several chest
muscles and the diaphragm. Inspiration is referred to as active since it involves contraction of
the chest muscles and movement of the diaphragm, while expiration is considered passive since
the chest muscles and diaphragm relax during this phase. The movement of air into and out of
the lungs is also caused by a change in air pressure inside and outside of the lungs during the act
of breathing. The rate of respiratory exchange is determined by the concentration of oxygen and
carbon dioxide in the blood.
The physician who specializes in treating patients with lung disease is called a pulmonologist.
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PROGRESS CHECK
1. What is the primary role of the nervous system?
_______________________________________________________________________
2. What are the two types of nervous tissue?
_______________________________________________________________________
_______________________________________________________________________
3. Afferent neurons are also known as ____________________________________ neurons.
4. The _______________________________________ gland is approximately the size of a
grape and is located in the central portion of the brain.
5. The _______________________________________ gland is located at the base of the
neck; it makes thyroxine which controls metabolism.
6. The _______________________________________ glands produce corticosteriods that
are responsible for regulating the mineral (salt) content of the blood.
7. What are the two major subdivisions of the circulatory system?
_______________________________________________________________________
_______________________________________________________________________
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The Human Body 35
PROGRESS CHECK
continued
8. The heart is enclosed in a membrane called the ________________________________ .
9. The term __________________________________ refers to the contraction of the atria;
__________________________________________ refers to the relaxation of the atria.
10. Define internal respiration.
_______________________________________________________________________
_______________________________________________________________________
11. The alveoli are the site where what occurs?
_______________________________________________________________________
12. The ______________________________________ is also known as the windpipe.
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PROGRESS CHECK ANSWERS
1. To serve as the master controlling and communicating system of the body.
2. Neuroglia and neurons
3. Sensory
4. Pituitary
5. Thyroid
6. Adrenal
7. Cardiovascular system and lymphatic system
8. Pericardium
9. Systole; Diastole
10. Internal respiration is the process by which gases (oxygen and carbon dioxide) are
exchanged between the blood and the body tissues.
11. The gas exchange between oxygen and carbon dioxide takes place.
12. Trachea
Copyright © 2015 | HIDA Educational Foundation
The Human Body 37
The digestive system
Digestion is the combined breakdown of food by both physical means (churning and chewing) and
chemical means (through the secretion of enzymes). Once we swallow food and it passes out of our
voluntary control, the digestive system takes over. The digestive system provides the body with
nutrients, water, and electrolytes (a substance that breaks down into positively- and negativelycharged particles in solution) needed for good health. The organs of this system are responsible
for food ingestion, digestion, absorption, and the elimination of the indigestible remains in the
form of feces. Essentially, the entire digestive system consists of a hollow tube extending from the
mouth to the anus, with various glands surrounding it that aid in the digestive process by secreting
substances into the tube.
Anatomy of the digestive system
The organs of the digestive system are separated into two major groups: the alimentary canal and
accessory digestive organs. The alimentary canal is coiled and twisted and is about 30 feet long.
The accessory structures consist primarily of salivary glands, gall bladder, liver, and pancreas,
which secrete their products into the alimentary canal.
Food enters the digestive tract through the mouth, or oral cavity, where it is mixed with saliva
and masticated (chewed). The tongue continually mixes the food with saliva so that the physical
and chemical breakdown of food begins before the food even leaves the mouth. Upon leaving
the mouth, the food enters the pharynx, a common passageway for both food and air. Alternating
muscle contractions within the pharynx propel food farther down into the digestive tract through
a wave-like motion called peristalsis. The esophagus extends from the pharynx through the
diaphragm to the stomach. It is approximately ten inches long and serves mainly to guide food into
the stomach through peristaltic action.
The stomach is also about ten inches long, but its diameter depends on how much food it contains.
When it is full it can hold over one-half gallon of food. The stomach acts as temporary storage
tank and as a site for food’s continued breakdown. Stomach muscles allow it not only to move
food along the tract but also to churn, mix, and pummel the food, physically breaking it down into
smaller fragments. Gastric juices are secreted into the stomach by gastric glands to aid in food
breakdown as well as absorption. After food has been fully processed in the stomach it resembles
heavy cream and is referred to as chyme.
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From the stomach, food enters the small intestine, the longest section of the alimentary canal. Its
average length is over ten feet. Nearly all food absorption occurs in the small intestine, which
is able to process only small amounts of food at one time. The small intestine is divided into
three sections: the duodenum (one foot long), the jejunum (three to four feet long), and the ileum
(seven feet long). The large intestine is next on the food digestion route, and is approximately
five feet long. The large intestine consists of the cecum, colon, rectum, and anal canal. Since most
of the food absorption is accomplished in the small intestine, the large intestine acts mostly as a
passageway for the elimination of unusable food in the form of feces.
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The Human Body 39
Accessory digestive organs
The pancreas is a soft, pink, triangular gland that plays a vital role in the digestive process because
it secretes a variety of enzymes that aid in the breakdown of digestible foods. The liver is the
largest gland in the body and one of the body’s most important organs. It is located under the
diaphragm and almost completely covers the stomach. Its digestive function is to produce bile,
which emulsifies (breaks down) large fat globules. The gall bladder is a small, green sac embedded
in the surface of the liver. The gall bladder stores bile and concentrates it by removing water from
it. The salivary glands empty their secretions into the mouth. Saliva helps moisten food, bind it
together, and as noted before, begins the process of food breakdown. The teeth obviously assist in
breaking food up into small pieces, making it easier for the digestive process to begin.
The urinary system
While other organ systems, like the respiratory and integumentary systems, play a role in the
excretion of certain body wastes, it is the urinary system that rids the body of most nitrogencontaining wastes, a by-product of protein breakdown. Organs of the urinary system include the
two kidneys, the two ureters, the bladder, and the urethra. The kidneys alone produce urine while
the other organs either transport it, store it, or eliminate it from the body. Let’s look at the structure
and function of each of these organs in more detail.
Structures and functions
The kidneys are small, bean-shaped, dark red organs that lie against the dorsal (back) wall of the
body near the lower part of the rib cage. Each kidney is about five inches long, three inches wide,
and one inch thick. A kidney is considered the second most complex organ in the body, after
the brain. In addition to ridding the body of wastes, the kidneys regulate the chemical makeup
of the blood to maintain proper balance between water and salts. Kidneys constantly filter the
blood ensuring that wastes can leave the body and that needed substances such as water, sugar,
and protein are retained. The renal artery and renal vein are responsible for bringing blood to
and from the kidney, respectively. The functioning unit of the kidney is known as a nephron.
Nephrons are tiny structures (there are over one million of them in each kidney). They filter the
blood and remove unwanted substances, reabsorb the substances that the body needs in order to
maintain homeostasis (balance or equilibrium), and secrete waste products in the form of urine for
elimination from the body. In 24 hours, the kidney’s two million nephrons filter approximately 35
to 45 gallons of blood and only produce about one to one and a half quarts of urine.
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The ureters are slender tubes about 10 to 12 inches in length that extend from the kidney to the
bladder. The ureters transport urine from the kidney to bladder. The bladder is a smooth muscular
sac with three openings—one for each ureter and one for the urethra. The bladder acts as a temporary
storage tank for urine and is well-suited for this due to its great expandability. When moderately
full, the bladder holds about one pint of urine but it is capable of holding twice that amount. The
urethra is the tube that carries urine from the bladder to the outside of the body. In males, the
urethra also functions to conduct sperm, as you’ll learn in the following section on reproduction.
Urologists and nephrologists are physicians that specialize in treating patients with kidney and
urinary system disorders.
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The Human Body 41
The reproductive system
Although the structures of the male and female reproductive system are different, they have
a common purpose – to produce offspring. In this section, we will explore the structures and
functions of both the male and female reproductive organ systems.
Male reproductive system
The primary male reproductive organs are the testes, also known as the gonads. Other reproductive
structures simply aid in the safe delivery of sperm to fertilize the female’s egg. The testes are
paired, oval in shape, and lie suspended within the scrotum. Inside the testes are seminiferous
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tubules, which are the actual sperm-producing “factories” of the male reproductive system. Sperm
production begins during puberty and continues throughout life. Every day the adult male produces
millions of sperm. The portion of the sperm that delivers the genetic material to the egg and helps
determine the specific characteristics of the offspring is known as the “head” of the sperm.
The hormonal product of the testes is testosterone, which is responsible for development of such
secondary sex characteristics in the male, such as the deepening of the voice, increased hair growth,
and augmented musculature. Accessory structures within the male reproductive system include
ducts through which sperm are conducted and glands that aid in fluid secretion for sperm mobility.
The vas deferens is the route the sperm take on their way out of the body and is the site at which
a vasectomy is performed, a procedure that results in male sterility. The prostate gland secretes a
milky fluid that aids in activating sperm into the urethra. The urethra is housed in the penis, which
is designed to deliver sperm into the female reproductive system. The male urethra has a dual
function: to carry sperm, and, as you learned in the section on the urinary system, to expel urine
from the body.
Female reproductive system
The role of the female reproductive system is much more complex than that of the male. The
female must not only produce ova (eggs) for fertilization by sperm, but she must also protect
a developing fetus during the nine months of pregnancy. The paired ovaries resemble almonds
and “house” the eggs which, until they mature, are called follicles. When a developing follicle is
mature enough to leave the ovary and begin its way down the female reproductive tract, the ovary
expels it in a process called ovulation. Ovulation usually occurs every 28 days, although this time
frame varies between women. The time in a woman’s life when ovulation and menstruation cease
is called menopause.
Ovaries, in addition to being a storage area for eggs, are hormone-producing organs. Estrogen,
which produces secondary sex characteristics in young women (such as breast development and
increased fat deposits in the hips and breasts), is one ovary-produced hormone. Another ovarian
hormone, progesterone, helps maintain a pregnancy and prepares the breasts for milk production.
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The Human Body 43
Like the male, the female also has a duct system that aids in reproduction. The fallopian tubes,
each of which is about 10 inches long and extends from above each ovary to the uterus, have
finger-like projections that pick up an expelled egg and move it toward the uterus. It is within a
fallopian tube that fertilization usually occurs, after sperm swim up the vagina, through the uterus.
The uterus is located between the bladder and the rectum and is about the size and shape of a pear,
except during pregnancy when it expands tremendously to accommodate a developing fetus. The
inside layer of the uterus is called the endometrium; this is where the fertilized egg implants itself
during development. If fertilization does not occur, this lining is sloughed off during menstruation,
exiting through the vagina, a muscular structure also referred to as the birth canal. The external
sex structures of the female include those located adjacent to the vagina, as well as the mammary
glands which are located in the breasts. The mammary glands contain ducts, or passageways,
through which milk travels prior to exiting via the nipple.
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PROGRESS CHECK
1. The organs of the digestive system are separated into two major groups. Name them.
________________________________________________________________________
________________________________________________________________________
2. Define peristalsis.
________________________________________________________________________
3. What is food called after it has been fully processed in the stomach?
________________________________________________________________________
4. What is the largest gland in the body and what does it secrete?
________________________________________________________________________
5. The functioning unit of the kidney is known as a
_______________________________________________________________________ .
6. The _______________________________________ are slender tubes about 10-12 inches
long that extend from the kidney to the bladder.
7. The primary reproductive organs of the male are the
_______________________________________________________________________ .
8. What is the endometrium?
________________________________________________________________________
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The Human Body 45
PROGRESS CHECK ANSWERS
1. The alimentary canal and the accessory digestive organs
2. The wave-like, muscular motion that propels food through the digestive tract
3. Chyme
4. The liver; it secretes bile
5. Nephron
6. Ureters
7. Testes
8. The inside layer of the uterus
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A
GLOSSARY
Abdominopelvic cavity: space below the chest in which the abdomen and pelvis lie
Abduction: motion of drawing away from the midline of an individual or organ
Adduction: motion of drawing toward the midline of an individual or organ
Adrenal glands: endocrine glands located on kidneys
Afferent: neurons that carry impulses from the sense organs to the central nervous
system; also called sensory neurons
Alveoli: thin-membraned sacs in lungs where oxygen and carbon dioxide are exchanged
Anatomy: the study, classification, and description of structures and organs of the
body
Anterior: toward the front
Apocrine gland: sweat glands, especially numerous in the armpits; their secretions are
thicker and more complex than the true sweat of eccrine glands
Appendicular: bones of both the upper and lower extremities
Autonomic nervous system: division of nervous system regulating involuntary
action; includes sympathetic and parasympathetic nervous systems
Axial: bones forming the longitudinal or lengthwise axis of the body, including the
vertebral column, the skull, and the thorax
B
Bile: fluid secreted by the liver, stored in the gallbladder, and transported to the
intestine to aid in digestion of fats
Bradycardia: slow rate of heart contraction, resulting in slow pulse rate
Bronchioles: terminal branches of the bronchi that connect to the alveoli
C
Cardiac muscle: involuntary muscle in perpetual use because it makes up the heart
Central nervous system (CNS): brain and spinal cord
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The Human Body 47
GLOSSARY
Chyme: mixture of partly digested food and digestive juices; forms a thick semi-liquid
mass and is found in the stomach and small intestine
Coronal plane: plane that passes through the body, separating it into front (anterior)
and back (posterior) portions
Coronary arteries: arteries which nourish the heart with blood
Cranial cavity: space inside the skull which houses the brain
D
Diastole: part of the heart cycle in which the heart chambers are filling with blood, i.e.,
the myocardial fibers are relaxing and lengthening
Distal: located farthest from a given point or farthest from the body center
Dorsal: toward the back
Duodenum: first part of small intestine
E
Eccrine gland: sweat gland
Efferent: neurons that transmit impulses from the central nervous system to muscles
and glands; also called motor neurons
Endometrium: inner layer of the uterus that is shed during menstruation or birth
Esophagus: gullet; connects pharynx and stomach
Estrogen: feminizing hormone produced by ovaries
Eustachian tubes: small ducts that connect the throat to the middle ear; equalizes
pressure between external and middle ear
Expiration: cycle of pulmonary ventilation where air is released from the lungs;
exhaling
F
Fallopian tube: ducts which take ovum from ovary to uterus
Follicles: spherical group of cells containing a cavity
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G
GLOSSARY
Gall bladder: accessory organ that aids in digestion by storing and concentrating bile;
but is not necessary for the body to survive
Gonads: organs that produce eggs or sperm
Gross anatomy: the study of the organs and parts of the body large enough to be seen
with the naked eye
H
Hemopoiesis: production of blood cells by the bone marrow
Homeostasis: state of relative equilibrium maintained by the body
I
Ileum: 12-foot section of the small intestine where bile salts and vitamin B12 are
absorbed
Inferior: in the direction of the feet, lower, or below
Insertion: movable bone to which muscles are attached
Inspiration: cycle of pulmonary ventilation where air is drawn into the lungs; inhaling
Isometric: contractions occurring continuously in postural muscles that stabilize
skeletal parts
Isotonic: contractions that shorten muscles and move bones
J
Jejunum: 8-10 foot section of the small intestine where protein, fat, and carbohydrates
are completely absorbed
K
Kidneys: cleans the blood by filtering out and eliminating metabolic waste products
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GLOSSARY
L
Large intestine: mixes the content of the intestine and stores feces in addition to
absorbing electrolytes and water; also called colon
Larynx: voice box
Lateral: located toward the sides or distant from the midline of a structure
Liver: largest internal organ weighing three to four pounds which lies on the right side
of the body immediately under the diaphragm protected from injury behind the lower
portion of the rib cage and sternum
Lungs: large, cone-shaped organs within the thorax that distribute air and exchange
gases with the bloodstream
M
Mammary glands: milk-producing glands in female breast
Masticated: chewed
Medial: located toward the midline
Menopause: cessation of menstruation
Menstruation: cyclical process of sloughing endometrial tissue from the uterus in the
absence of pregnancy
Microscopic anatomy: the study of the microscopic structure of the tissues and cells
Midsagittal plane: plane that passes through the center or midline of the body and
divides it into left and right halves
Myocardial infarction: heart attack caused by an obstruction of the flow of blood to
an area of the heart muscle
Myocardium: heart muscle
N
Nasopharynx: upper division of the pharynx extending from the posterior nares to
the soft palate
Nephron: microscopic, urine-forming unit in the kidney made up of a renal corpuscle
and a renal tubule
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O
GLOSSARY
Origin: describes the stationary bone to which muscles attach
Osteomyelitis: inflammation of the bone, either acute or chronic, caused by a bacterial
infection
Ova: (singular, ovum) eggs
Ovaries: female reproductive organs which produce eggs
Ovulation: release of an egg
P
Pancreas: glandular organ lying below and behind the stomach, performs both
endocrine and exocrine functions in the body
Parathyroid gland: one of four endocrine glands flanking thyroid
Parietal: pertains to or forms the wall of a body cavity
Penis: male reproductive organ through which urethra travels
Pericarditis: inflammation of the pericardium
Pericardium: membranous sac which seals heart from chest
Peripheral nervous system: nerves that lead to CNS
Peristalsis: wave of contraction
Pharynx: throat
Physiology: the study of the process and function of the human body
Pituitary gland: endocrine gland in brain known as “master gland”
Pleura: (plural, pleurae) thin, moist, serous membrane lining the outer surface of the
lungs, inner surface of the rib cage, and the top of the diaphragm
Pleurisy: inflammation of the pleural membrane
Posterior: toward the back
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GLOSSARY
Progesterone: ovarian hormone that stimulates uterus to prepare for pregnancy
Prostate gland: organ at the base of the male bladder; contributes alkaline fluid to
semen
Proximal: located near or occurring close to the body’s center or specific reference
point
S
Sagittal plane: plane that divides the body into right and left halves
Scrotum: sac which contains the testes
Sebaceous gland: oil-producing skin gland associated with hair follicle
Seminiferous tubules: coiled vessels within testes and where spermatogenesis occurs
Skeletal muscle: voluntary muscle that attaches muscles to tendons that attach to bone
Small intestine: approximately 23 feet of coiled tube that is the main site of the body’s
digestion and absorption of fat
Somatic nervous system: portion of the peripheral nervous system concerned with
voluntary muscle motions and reflexive muscle activity, like the withdrawal from pain
Smooth muscle: involuntary, slow-contracting muscle of internal organs
Sperm: male sex cell; carries half the genetic complement and unites with an egg
Spinal cavity: space along the backbone in which the spinal cord lies
Superior: in the direction of the head, up, or above; sometimes called cranial or
cephalad
Systole: part of the cardiac cycle in which the heart is in contraction, i.e., the myocardial
fibers are tightening and shortening
T
Tachycardia: heart rates that are faster than 100 beats per minute
Testes: sperm-producing organ which also secretes male hormone, testosterone
Testosterone: masculinizing hormone
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GLOSSARY
Thoracic cavity: space inside the chest containing the heart and lungs
Thyroid gland: endocrine gland at base of neck
Trachea: windpipe
Transverse plane: plane that divides the body into upper and lower halves
U
Ureters: vessels that take urine to bladder
Urethra: vessel that excretes urine
Urinalysis: laboratory urine test of renal function
Urine: watery waste
Uterus: organ that nurtures zygote as it grows into a baby
V
Vas deferens: seminal duct that travels to urethra
Ventral: toward the front
Visceral: locates something on the covering of an organ
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The Human Body 53
APPENDIX
WORD ROOTS AND COMBINING FORMS,
SUFFIXES, AND PREFIXES
Word Roots and Combining Forms
abdomin/o
aden/o adren/o alb amaur andr/o angi/o arteri/o ather/o arthr/o audi/o blast/o bronchi/o bucca calc carcin/o cardi/o cent cephal/o cerebr/o cervic/o chlor chondr/o chrom cide clast col/o colecyst/o
colp/o cost/o
crani/o
crin 54
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abdomen
gland
adrenal glands
white
dark
man
vessel
artery
fat deposit
joint
hearing
bud, growth
bronchus
cheek
calcium
cancer
heart
to puncture or pierce
head
brain
neck
green
cartilage
color
to kill
to break
colon
gallbladder
vagina
ribs
skull
to secrete
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APPENDIX
cutane/o
cyan/o
cyst/o
cyt/o
derm/o
desis
edema
encephal/o
enter/o
eosin/o
erythr/o
esophag/o
gastr/o
glucos/o
glyc/o
gyn/o
hem/o
hemangi/o
hepat/o
hist/o
hydr/o
hyster/o
laryng/o
leuk/o
lingu/o
lip/o
lith lymph/o
melan/o
nmr my/o
myel/o
narc necr nephr/o
neur/o
ocul/o
oo/o Copyright © 2015 | HIDA Educational Foundation
skin
blue
bladder
cell
skin
to stick together
swelling
brain
intestine
red
red
esophagus
stomach
sugar
sugar
woman
blood
blood vessel
liver
tissue
water
uterus
larynx
white
tongue
fat
stone
lymph
black
wall
muscle
bone marrow, spinal cord
to sleep
death
kidney
nerves
eye
ova
The Human Body 55
APPENDIX
56
The Human Body
orchid/o
oste/o
ovari/o
pancreat/o
path/o
pector/o
ped/o
pelv/i
phag/o
phas phren/o
pleg proct/o
proxim
psych
pulmon/o
purpur
py ren/o
reticul/o
retin/o
rhag salping/o
schiz, shis
spermat/o
splen/o
steth/o
stomat/o
thorac/o
thym/o
thyr/o
urethr/o
uter/o
vagin/o
vas/o
ven/o
zyg/o
testes
bone
ovary
pancreas
disease
chest
foot
pelvis
eat
speech
diaphragm
paralysis
rectum
near
mind
lung
purple
pus
kidney
network
retina
flow
fallopian tubes
split
sperm
spleen
chest
opening
chest
thymus gland
thyroid gland
urethra
uterus
vagina
vessel
vein
paired, united
Copyright © 2015 | HIDA Educational Foundation
APPENDIX
Suffixes
-algia pain
-cele swelling
-crine to secrete
-dynia pain
-eclasis dilation
-ectomy surgical removal
-emia blood
-gen producing
-gram record
-graph instrument
-itis inflammation
-oma tumor
-osis harmful condition or process
-philic loving
-phobic fearing
-plasia
formation
-plasm
material
-plasty
surgical formation
-porosis
pores or cavities
-scope
instrument
-stasis stopping
-storey
make an opening
-taxis movement
-tomy incision
Prefixes
a
ab
ad
ambi- an
ante
apo
Copyright © 2015 | HIDA Educational Foundation
no, not, or without
indicates a body part opposite to or removed from another
indicates motion toward
both
not or without; absent or deficient
before or in front of
away from
The Human Body 57
APPENDIX
58
The Human Body
brady- slower
chemo- indicates chemicals or chemical reactions
circum- around or on all sides of
con
together, with
dextr- to the right of
dia
through or throughout: across or by transmission
dors
indicates the dorsal or back area
dys
diseased, difficult, faulty, disordered, painful
ecto
indicates the outside, external part, or surface
endo
indicates the inside or within
epi
upon, over, around, toward, close to, or in addition to
exo
outside of, external to, or beyond
hetero- other, another, or different
homeo- like or similar
homo- the same or like
hyper- above, at a higher point, abnormally high, excessive
hypo- below, at a lower point, abnormally low, deficient
infra
below, inferior to, after
inter
between or among, together
intra
within or inside of
juxta- near
later
to the side of
medi- in the middle of
meso- in the middle of
meta
located behind or beyond, later, changing, or alternating
micro- small
neo
new or recent
para
alongside, near, beyond, harmful, resembling
peri
indicates encircling or close at hand
phago- indicates eating or destroying
pino
refers to drinking
poly
many
post
alter in time or position
pre
at an earlier time
pseudo- indicates a deceptive similarity
retro
backward or behind
scler
indicates hardness or affects sclera of eye
Copyright © 2015 | HIDA Educational Foundation
APPENDIX
subsupersupratachytrans-
beneath, inferior or less than, subordinate
placed above, superior, exceeding the norm
placed above or greater than
swift or accelerated
across, beyond, transferring, changing
Prefixes Indicating Numbers
monounibibindidiplodisterriquadquadritetrapentaquintihexsexheptiseptoclanonadecamicrodecihectokilo-
Copyright © 2015 | HIDA Educational Foundation
one
one
two, twice
two, twice
two, twice
two, twice
two, twice
three, third
three, third
four
four
four
five
five
six
six
seven
seven
eight
nine
ten
one one-hundredth
one tenth
hundred
thousand
The Human Body 59
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