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Cardiovascular and
8
Respiratory Systems
Chapter Objectives
● Describe the function of the cardiovascular system.
● Describe the chambers of the heart and their
function.
● Describe the location and function of the valves of
the heart.
● Describe the three tissue layers of the heart wall.
● List the structures of the vascular system.
● Briey describe blood circulation through the
myocardium.
● Describe the cardiac cycle.
● Name and locate the components of the heart’s
conduction system.
● Dene common terms that describe variations in
heart rates.
● Identify common types of heart disease.
● List risk factors for coronary artery disease.
● List common diagnostic exams used to detect
cardiovascular disorders.
● Describe common approaches to the treatment of
heart disease.
● List the different types of blood vessels.
● List common disorders of the circulatory system.
● Explain the process of respiration and the factors
that control respiration.
● Name and describe all the structures of the
respiratory system.
● Discuss the processes of internal and external gas
exchange.
● Explain the process for the transportation of oxygen
and carbon dioxide in the blood.
● List common types of respiratory disorders.
● List the common procedures and treatments used
for respiratory diseases.
CAAHEP & ABHES Competencies
CAAHEP
● Describe structural organization of the human body.
● Identify body systems.
● List major organs in each body system.
● Describe the normal function of each body system.
● Identify common pathology related to each body
system including signs, symptoms, and etiology.
● Analyze pathology for each body system including
diagnostic measures and treatment modalities.
ABHES
● List all body systems, their structure, and
functions.
● Describe common diseases, symptoms, and
etiologies as they apply to each system.
● Identify diagnostic and treatment modalities as they
relate to each body system.
151
152 Section II Anatomy and Physiology
Chapter Terms
Aneurysm
Apex
Arrhythmia
Arteriosclerosis
Atherosclerosis
Atrioventricular valve
Bradycardia
Bronchodilators
Bronchoscope
Carbaminohemoglobin
Cardiologist
Abbreviations
ARDS
AV
bpm
CABG
COPD
Case Study
Catheterization
Coronary angiography
Coronary
Deoxygenated
Diastole
Dysrhythmia
Endocardium
Effusion
Epicarditis
Epicardium
Epistaxis
CO
2
CPR
CT
ECG/EKG
MI
Hypertension
Hypotension
Ischemia
Murmur
Myocarditis
Myocardium
Necrosis
Oxygenated
Oxyhemoglobin
Pericarditis
NSR
O
2
PAC
PAT
PTCA
Pericardium
Plaque
–pnea
Semilunar valve
Sinus rhythm
Spirometer
Stenosis
Systole
Tachycardia
Thrombosis
PVC
RSV
SA
TB
URI
Mr. Hoffman is a 54-year-old patient who arrives
at Dr. Ashton’s ofce because he has been short of
breath, quite fatigued, and experiencing dizziness.
As the receptionist is checking in Mr. Hoffman, she
notices that he is holding his chest and is sweat-
ing. She immediately calls for Dr. Ashton’s medi-
In this chapter, we will explore the cardiovascular and
respiratory systems. The heart and lungs work together in
concert to keep the blood owing through the body carrying oxygen to the body cells and removing carbon dioxide.
C
O
G
THE CARDIOVASCULAR
SYSTEM
The cardiovascular system includes the heart and the
blood vessels. The heart pumps the blood, which travels
through the blood vessels. One of the main functions
of the blood is to carry oxygen to the body cells and
return carbon dioxide to the lungs to be exhaled by the
body. The system of blood vessels is also referred to as
the circulatory system since their function is to provide
circulation throughout the body. It is a one-way system
with the blood traveling only in one direction.
cal assistant, Carlos, to escort Mr. Hoffman to an
examination room. Once in the exam room, Carlos
obtains a pulse, respiration, and blood pressure on
Mr. Hoffman, which are P 100, R 22, and BP 160/94.
Carlos immediately noties Dr. Ashton of
Mr.Hoffman’s vital signs and condition.
C
O
G
THE HEART
The heart begins beating when the fetus is developing
in the womb and stops when we die. During that time,
it beats continuously approximately 70 to 80 beats per
minute. The rate can increase or decrease depending on
the body’s need for additional oxygen and nutrients. As
you start to explore the structures of the heart, refer to
Case Question
A
F
F
If you are Dr. Ashton’s medical assistant,
how would you reassure Mr. Hoffman
if he is extremely worried about his
condition?
Chapter 8 Cardiovascular and Respiratory Systems 153
Figure 8-1, which shows the heart and major blood vessels leading in and out of the heart. Notice the right side
is blue and the left side red indicating oxygen-rich blood
ows through this side.
Heart Structure
The adult heart is approximately the size of a st. It is
located slightly to the left of the midline of the body in
the
mediastinum, which is in the central area of the chest
cavity. The lower, rounded area of the heart is called the
apex. The heart is a hollow organ with three layers:
Endocardium—the innermost lining of the heart cov-
r
ering the inside of the heart chambers and heart valves
Myocardium—the muscular layer of the heart (car-
r
diac muscle)
Epicardium—the outermost layer, which also serves
r
as the visceral (organ) layer of the pericardium
Chambers of the Heart
The heart is a double-sided pump receiving deoxygenated blood from the body into the right side and pumping oxygenated blood back out to the body from the left
side. Oxygenated blood is blood that is rich in oxygen,
deoxygenated blood has less oxygen and will
and
return to the lungs to pick up more oxygen. The heart is
divided into four chambers with each one having a function in the circulation of blood through the heart. The
chambers include the following:
Right atrium—upper chamber that receives deoxy-
r
genated blood from body
Right ventricle—lower chamber that receives blood
r
from the right atrium and pumps it to the lungs
Left atrium—upper chamber that receives oxygen-
r
ated blood from the lungs
Left ventricle—lower chamber that receives blood
r
from the left atrium and pumps it out to the body
The right and left chambers are separated by a wall
called the septum. Specically, the interatrial septum
separates the atria and the interventricular septum separates the ventricles. The walls are primarily made up of
myocardium, heart muscle.
Heart Valves
The function of the heart valves is to ensure that blood
continues to ow in one direction and not backow. The
heart valves separating the atria and ventricles are called
the atrioventricular valves (AV). The valves that allow
Superior vena cava
Right pulmonary
artery
(branches)
Ascending
aor
ta
Right
pulmonary
veins
Right
atrium
Tricuspid
valve
Right ventricle
Inferior
vena cava
Blood high in oxygen
Blood low in oxygen
Pulmonic valve
Endocardium
Brachiocephalic artery
Left common carotid artery
Left subclavian artery
Myocardium
Epicardium
Aortic arch
Pulmonary artery
Interventricular
septum
Left pulmonary
arter
Left
pulmonary
veins
Left atrium
Aortic valve
Mitral
(bicuspid)
valve
Apex
y (branches)
Left
ventricle
Figure 8-1 Heart and blood
vessels. The right heart has
blood low in oxygen; the
left heart has blood high
in oxygen. The arrows show
the direction of blood ow
through the heart. (Reprinted
from Cohen BJ. Memmler’s
The Human Body in Health
and Disease. 13thed.
Philadelphia, PA: Wolters
Kluwer; 2014.)
154 Section II Anatomy and Physiology
blood to exit the heart into major blood vessels are
called semilunar valves because they resemble a halfmoon shape. Each valve is named separately.
Tricuspid valve—has three (tri) cusps or aps, also
r
called the right atrioventricular valve (AV) allowing
blood ow from the right atrium into the right ventricle
Mitral valve—has two cusps, also called the bicus-
r
pid valve and left atrioventricular valve (AV) allowing blood to ow from the left atrium into the left
ventricle
Pulmonary valve—a semilunar valve that allows
r
blood ow from the right ventricle into the pulmonary blood vessels leading to the lungs
Aortic valve—a semilunar valve that allows blood
r
ow from the left ventricle to the aorta then to the
body
The Pericardium
The heart is enclosed in a brous sac called the pericar-
dium
. It has two serous layers, the parietal layer that
lines the pericardial sac and a visceral layer (epicardium)
that adheres to the surface of the heart. Pericardial uid
is found between the outer brous sac and the serous
lining. This uid acts as a lubricant allowing the heart to
move freely with each beat, reducing friction.
The Myocardium
Now that we have an overview of the heart structures,
let’s go back and focus on the heart muscle, the myocardium. Cardiac muscle is involuntary; it contracts
without conscious thought. The muscle cells are tightly
joined with adjacent cells with specialized membrane
proteins. These allow the electrical impulses to travel
between the cells. These impulses are required for the
heart to be stimulated to beat.
as a cardiac cycle. As the atria relax, blood is allowed
to ll the atria. This happens when the ventricles are
contracting to empty the blood in preparation of receiving blood from the atria on the next beat. Cardiac output is the amount of blood pumped by each ventricle in
1minute. During exercise, the cardiac output increases
as much as two to four times greater than at rest.
The Conduction System of the Heart
As mentioned earlier, the heart muscle functions by electrical stimulation that travels from cell to cell. The heart
muscle has structures called nodes that generate the electrical activity. The nodes conduct the electricity throughout
the heart muscle causing contraction. Figure 8-2 shows
the components of the conduction system of the heart.
The structures of the conduction system include the
following:
Sinoatrial (SA) node—located in the upper wall of
r
the right atrium; called the pacemaker of the heart
because it sets the rate of heart contractions
Atrioventricular (AV ) node—located in the septum
r
between the atria at the bottom of the right atrium
Atrioventricular (AV) bundle—also called the bundle
r
of His, is located at the top of the septum between the
ventricles
Right and left bundle branches—bers imbedded
r
down both sides of the septum between the ventricles
Purkinje bers—network of bers that branch
r
throughout the myocardium
Sinoatrial
node
Left
atrium
Myocardium Blood Supply
The blood owing through the heart does not provide
the oxygen and nutrient to the myocardium. The myocardium has its own blood vessels, the coronary blood
vessels. The term coronary comes from the word crown,
which is how the vessels encircle the heart. The coronary
vessels branch off of the aorta as it exits the heart carrying oxygenated blood to the body.
Heart Function
The heart is the pump that keeps the blood owing
throughout the body. The chambers of the heart contract
and relax. When the upper chambers, the atria, are contracting, the lower chambers, the ventricles, are relaxing.
The active, contracting phase is called
resting, relaxing phase is known as diastole. Each heartbeat consists of a systole and diastole. This is referred to
systole, and the
nodal
Inter
pathways
Right atrium
Atrioventricular
node
ioventricular
Atr
bundle (bundle
of His)
Right and left
bundle branches
Figure 8-2 Electrical conduction of the heart.
(Reprinted from Cohen BJ. Memmler’s The Human Body
in Health and Disease. 13th ed. Philadelphia, PA: Wolters
Kluwer; 2014.)
Purkinje fibers
Chapter 8 Cardiovascular and Respiratory Systems 155
A heartbeat starts with the SA node generating an
electrical impulse, which travels to the AV node and then
to the bundle of His. The impulse travels down the right
and left bundle branches and then to the Purkinje bers
initiating the contraction of the heart. A normal heart
rhythm is called
tors that can affect the heart’s rate. The nervous system
responds to changes in the body, which may affect the
heart rate. For example, stress and excitement will cause
an increase in the heart rate, and when the body is at
rest, the heart rate will be lower. Terms used to describe
variations in heart rate are as follows:
Bradycardia—slow heart rate of <60 beats per min-
r
ute (bpm) but usually will not drop below 50 bpm.
Tachycardia—rapid heart rate of more than 100
r
bpm, which is normal during exercise.
Sinus arrhythmia—a variable heart rate due to
r
changes in the rate and depth of respirations, which is
considered a normal occurrence.
Premature ventricular contraction (PVC)—a ventric-
r
ular contraction that starts with the Purkinje bers
rather than the SA node. It is felt as a palpitation or
skipped beat, which might be caused by caffeine or
stress.
sinus rhythm. There are many fac-
Diagnostic Heart Exams
In order to determine the health of the heart, the physician begins by listening to the heart sounds and rhythm
with a stethoscope. In addition to heart rate variables,
there may be abnormal heart sounds. One of the abnormal sounds is a
that fails to close tightly and blood leaks back. Another
sound is caused from a narrowing of the valve opening
called a
stenosis.
Electrocardiograph (ECG or EKG)
The ECG is used to record the electrical activity of the
heart. This procedure is discussed in the chapter on
Diagnostic Testing. The ECG traces the activity of the
heart indicating any myocardial problems that might
affect the conduction and cardiac cycle of the heart. The
procedure utilizes sensors or electrodes placed on the
patient’s skin on the arms, legs, and specic locations on
the chest. The electrical activity is picked up by the sensors, sent to the electrocardiograph machine, and shows
as waves on the ECG tracing. The waves are identied
by the letters P, Q, R, S, T, and U. Each heartbeat is represented by a complex of these letters, which correspond to
a specic function of the heart including the following:
murmur caused by a faulty heart valve
R wave—measures electrical activity through the left
r
ventricle of the heart.
QRS complex—electrical activity of the ventricles as
r
they pump out blood to the body.
S-T segment—time period between the end of the
r
contraction of the ventricles and the beginning of the
period when the ventricles are resting.
T wave—the resting period of the heart before the
r
next cardiac cycle begins.
U wave—extra wave sometimes seen after the T wave
r
in someone whose heart has a slow recovery time possibly due to low potassium level or other metabolic
problem.
A
cardiologist, a heart specialist, uses the ECG to
monitor changes in the waves and intervals to determine
heart injury and arrhythmias.
Invasive Cardiac Procedures
When it is determined that a patient has heart disease
or injury, there are procedures that might be performed
to identify the location and extent of the damage. Some
procedures are also used to identify and prevent heart
disease. Heart
used to diagnose or treat conditions affecting circulation in the coronary arteries. A catheter, a exible tube,
is inserted into a blood vessel either in the arm or in the
groin. The catheter is guided to the heart while a uoroscope, an instrument for examining using x-rays, shows
the path of the catheter and any abnormalities. Blood
samples and pressure measurements can be obtained
during this procedure.
When indicated,
performed during catheterization. A dye is injected into
the coronary arteries to highlight any vessel damage or
blockage. Computerized tomography (
used to visualize the coronary arteries.
Ultrasound, high-frequency sound waves, can also
be used to detect abnormalities in the heart and vessels.
The sound waves are emitted from the ultrasound device
and are directed at the heart. As the sound wave echoes
bounce off the heart structures, the echoes are traced on
an electronic instrument and recorded on lm. This procedure called echocardiography provides an immediate
view of the heart activity. It is a noninvasive procedure
but allows the examiner to witness the actual function
of the heart.
C
O
G
catheterization is an invasive procedure
coronary angiography may also be
CT) may also be
CARDIAC DISEASE
P wave—this wave represents the contraction of the
r
atria, depolarization.
P-R interval—the electrical activity of the atria as
r
they pump out blood.
Heart and circulatory diseases cause damage to the
heart structures and blood vessels. This includes structural defects, inammation, valve malfunctions, and
abnormal rhythms.
156 Section II Anatomy and Physiology
Heart Inammation
As with other structures and organs of the body, the heart
can become inamed and infected. Heart inammation
can be caused by bacteria, viruses, autoimmune diseases,
and toxins. Specic medical terms are used to describe
the location of the inammation. When the three layers
of the heart are involved, the terms include the following:
Pericarditis—inammation of the sac around the
r
heart
Myocarditis—inammation of the heart muscle,
r
which could lead to necrosis (death of tissue) of the
area of heart muscle affected
Endocarditis—inammation of the lining of the heart,
r
which may involve the valves since they are covered
by the endocardium
Rhythm Abnormalities of the Heart
Arrhythmia, also called dysrhythmia, is the term used
to describe an abnormal heart rhythm. An arrhythmia is
caused by a dysfunction within the conduction system of
the heart. Two main types of arrhythmia include a utter,
which is an extremely fast heartbeat that may be up to
300 times a minute. The rate is fast, but the contractions
are coordinated, not erratic. Fibrillation describes a very
rapid rate; however, the contractions are uncoordinated.
Fibrillation may involve the upper chambers, the atria
or the lower chambers, the ventricles, or both. Although
atrial brillation is a problem, the ventricles are responsible for the forceful systole of the heart so ventricular
brillation is a more serious condition. A debrillator is
used to correct brillation. It is a device that delivers a very
strong electrical current to convert the brillation into a
normal rhythm. You may have seen one of these devices
in public areas for use in case of emergency. Physician
ofces have a debrillator on the ofce crash cart.
Heart block is a condition when there is an interruption of the electrical impulse. The normal pacemaker of
the heart, the SA node, may be defective and unable to
generate a normal impulse. Heart block may be caused
from damage to the heart muscle due to prior infections,
heart attack, and the aging process. Table 8-1 lists the
types of arrhythmias, symptoms, and possible causes.
Congenital Heart Disease
Conditions that are present at birth are termed congenital and may be the result of defects developing while the
fetus is growing in the womb. As the heart and blood
Table 8-1
Type of Arrhythmia Indications and Symptoms Possible Causes and Consequences
Sinus tachycardia Abnormally rapid heartbeat (100–180 bpm)
Sinus bradycardia Abnormally slow heartbeat (<60 bpm), but
Paroxysmal atrial
tachycardia (
Premature atrial contraction (
Premature ventricular
contraction (
Ventricular tachycardia (V tach)
Ventricular brillation
(V b)
Heart Arrhythmias
PAT)
PAC)
PVC)
resulting in decreased ventricular lling and
low blood pressure
with a normal rhythm
Sudden, temporary onset of a heartbeat of
180–250 bpm, often accompanied by patient
weakness and the feeling of a pounding or
uttering in the chest
An electrical impulse starts in the heart before
the next expected beat; patient may complain of feeling an “extra” or “skipped” beat
Ventricles contract before the next expected
beat; patient may complain of feeling an
“extra” or “skipped” beat; can be more serious
than PAC
Heart rate exceeds 100 bpm with 3 or more
PVCs per minute; results in decreased cardiac
output; patient may complain of pressure and
the feeling that the heart is “beating out of my
chest”
Ventricles begin twitching, making the heart’s
pumping action ineffective and stopping the
circulation of blood
Dehydration, extreme anxiety, heart failure,
or hemorrhage can also result from intense
exercise
Can result from myocardial infarction or
certain medications (such as digoxin); is
also often seen in well-conditioned athletes
Extreme anxiety or stress, excessive stimulants (such as nicotine or caffeine); also
can have no known cause
Thyroid disease, heart disease, central nervous system imbalances, stress, or excessive
use of stimulants
Electrolyte imbalances, caffeine or other
stimulants, anxiety or stress; may also be a
sign of pulmonary disease or an injured or
diseased heart
Similar to causes of PVCs; the longer V
tach lasts, the more serious it is because
cardiac output drops and the blood supply
to organs is decreased; unchecked V tach
can lead to V brillation
The most serious of all arrhythmias; death
will result if not immediately treated with
CPR, a debrillator, or cardiac drugs
Chapter 8 Cardiovascular and Respiratory Systems 157
vessels are being formed, there are some defects that
may result in malfunction of the structures. Some of the
congenital conditions include:
Foramen ovale—small hole in the interatrial septum
r
allowing blood to ow directly from the right atrium
into the left atrium before it has traveled to the lungs
to pick up oxygen (hole in the heart).
Ductus arteriosus—which by the name means a duct
r
(blood vessel) between arteries that connects the pulmonary artery and the aorta; instead of blood leaving
the heart in the pulmonary artery going to the lungs
for oxygenation, blood ows into the aorta.
Ventricular septal defect—opening in the interventric-
r
ular septum allowing blood to ow from the left side
of the heart into the right side.
Coarctation of the aorta—the aortic arch is narrowed
r
restricting blood ow out of the heart.
Tetralogy of Fallot—a combination of defects that
r
includes pulmonary artery stenosis (narrowing),
interventricular septal defect, aortic displacement to
the right, and right ventricular hypertrophy (overdevelopment, increased size); commonly called a “blue
baby” due to severe cyanosis (lack of oxygen).
Most of the congenital defects correct on their own,
or heart surgery is indicated for more serious conditions.
Heart Conditions and Disorders
There are numerous heart diseases, conditions, and
disorders that affect the structures of the heart causing
malfunctions.
Valve Malfunction
As discussed earlier, the valves in the heart have one function, which is to keep the blood owing in one direction.
Valves can narrow reducing the amount of blood ow
to the next chamber or vessel. This condition is called
valvular stenosis. A valve may not close properly allowing backow of blood. This condition is referred to as
valvular insufciency. Valves can become damaged and
ineffective due to inammation and infections that
attack the heart’s endocardial layer. Rheumatic heart
disease results from a streptococcal infection, rheumatic
fever. The mitral valve is the most commonly affected
valve due to this infection. The valve loses some of the
exibility and thickens not allowing it to open and close
properly.
Coronary Artery Disease
The coronary arteries are the vessels that supply the
heart muscle with their blood supply. When they become
diseased, the blood ow to the myocardium is affected.
Atherosclerosis is a condition caused by a buildup of
plaque (fatty deposits). The space inside the vessels
becomes narrow leading to decreased blood ow. The
lack of blood supply is called ischemia. The inside of
the vessel becomes rough causing a higher risk for blood
clot formation,
thrombosis. Figure 8-3 shows how the
coronary vessel becomes affected with atherosclerosis.
Angina pectoris can also be caused from coronary
artery disease. The patient experiences chest pain that
may radiate into the jaw, neck, and upper back. It is
frequently confused with heartburn. Medication (nitroglycerin) is used to help open the vessels allowing better
blood ow.
Myocardial Infarction
Commonly known as a heart attack, myocardial infarction (MI) is caused from obstruction of blood ow to
the myocardium. The portion of the heart that does
Fat deposits
(plaque)
Figure 8-3 Coronary atherosclerosis. A. Fat deposits (plaque) narrow an artery, leading to ischemia (lack of blood
supply).
to myocardial infarction (MI). (Reprinted from Cohen BJ. Memmler’s The Human Body in Health and Disease. 13th ed.
Philadelphia, PA: Wolters Kluwer, 2014.)
B. Plaque causes blockage (occlusion) of a vessel. C. Formation of a blood clot (thrombus) in a vessel leads
BCA
Blockage
(occlusion)
Blood clot
(thrombus)
158 Section II Anatomy and Physiology
not receive blood will begin the process of necrosis
(tissue death). It is critical that the patient recognize
the signs and symptoms and seek immediate attention.
If untreated, many people die from heart attack within
the rst hour from the onset of symptoms. Symptoms of
MI can include the sudden onset of chest pain, radiating pain to the left arm and jaw, shortness of breath,
sweating, nausea, and anxiousness. The heart’s electrical
activity is also affected, causing it to stop beating. At
this point,
cated. Debrillation may also be indicated. Drugs are
also administered to dissolve the clots.
A
F
F
After Dr. Ashton examined him, he asked Carlos,
the medical assistant, to give Mr. Hoffman nitroglycerin and to do an electrocardiogram. The
ECG shows that Mr. Hoffman still has tachycardia, but his ECG shows that his heart is in normal sinus rhythm (
feeling much better. Dr. Ashton asks Carlos to
set up an appointment for Mr. Hoffman to see
the cardiologist who has a practice in the same
medical building. Why do you think the physician wants Mr. Hoffman to see the cardiologist?
ably perform on Mr. Hoffman?
CPR (cardiopulmonary resuscitation) is indi-
Case Questions
Let’s see how Mr. Hoffman is doing. He
is lying on the examination table and
appears to be a little more comfortable.
NSR). Mr. Hoffman says he is
What examinations will the cardiologist prob-
Heart Medications
Patients with heart disease typically require medication
to help strengthen the heart, decrease uid retention,
lower blood pressure, and lower cholesterol. These are
some of the medications used to treat heart conditions:
Statin drugs—lower cholesterol and inhibit the liver
r
manufacture of cholesterol
Anticoagulants—prevent clot formation; aspirin may
r
be used on a daily basis when recommended by the
physician
Digitalis—strengthens heart muscle contractions
r
Beta-blockers—reduce the rate and strength of heart
r
contractions
Antiarrhythmic agents—regulate the rate and rhythm
r
of the heartbeat
Calcium-channel blockers—dilate vessels and control
r
the force of heart contractions
Thrombolytics—dissolve blood clots (thrombus)
r
Pacemakers
The SA node is the pacemaker of the heart generating
the heartbeats and keeping them regular and normal.
When the SA node fails, a mechanical device, an articial
pacemaker, is implanted to take over this function. The
pacemaker is an electric, battery-operated device that
supplies impulses to the heart. The device is implanted
under the skin in the upper left side of the chest. A wire
from the pacemaker is placed in the heart muscle.
Heart Surgery
Heart Failure
This condition occurs when the heart cannot pump efciently and it is failing. It may occur from disorders such
as damage to the heart and valve malfunction, which
put stress on the heart. As the condition progresses, the
heart is unable to pump the blood out to the body. Blood
backs up in the ventricles and causes increased pressure
in the heart. The patient begins to experience uid retention in the extremities, and uid builds up in the lungs
causing shortness of breath. When the uid retention is
present, physicians refer to the condition as congestive
heart failure.
C
O
G
When patients are diagnosed with heart conditions
and disease, the primary care physician will often
refer the patient to a cardiologist, heart specialist, for
a full evaluation, treatment, and monitoring of the
condition.
TREATING HEART DISEASE
In some cases, it might be necessary to correct heart
problems with surgery. Patients may be placed on a
heart–lung machine during surgery allowing the blood to
bypass the heart yet still be circulated to the body supplying oxygen. Types of heart surgery include the following:
Percutaneous transluminal coronary angioplasty
r
(PTCA)—catheter with balloon inserted into a vessel to
open the lumen of an atherosclerotic vessel. Figure 8-4
demonstrates how the PTCA procedure is performed.
Coronary artery bypass graft (CABG)—healthy seg-
r
ments of blood vessels are used to bypass coronary
artery obstructions, and a section of vein from the leg
is usually used.
Angioplasty—a balloon is inserted into the restricted
r
artery and inated increasing the size of the lumen
(inside opening) of the artery, which increases blood
ow through the artery.
Stent—a small tube inserted in the blood vessel to
r
keep it open.
Coronary atherectomy—removal of plaque from the
r
walls of the coronary arteries.
Heart transplant—surgical replacement of the heart and
r
sometimes the lungs using a compatible donated heart.
Chapter 8 Cardiovascular and Respiratory Systems 159
Wall
of coronary
artery
Plaque
Catheter in
balloon
place;
deflated
A
Balloon
inflated
B
Catheter
C
Figure 8-4 Coronary angioplasty. A. A guide catheter is threaded into the coronary artery. B. A balloon catheter is
inserted through the occlusion and inated.
vessel is opened. (Reprinted from Cohen BJ. Memmler’s The Human Body in Health and Disease. 13th ed. Philadelphia,
PA: Wolters Kluwer, 2014.)
Obviously, the best way to avoid these heart surgeries is
to keep your heart healthy. There are some risk factors
for heart disease that cannot be managed that include
age, gender, heredity, and body type. There are many
things that we can change or modify to help avoid the
risk of heart disease. These include not smoking, maintaining physical activity, managing weight control, and
watching the diet. Diets should be lower in saturated
fats and sodium. Diseases such as hypertension and diabetes also may put someone at a greater risk to develop
C. The balloon is inated and deated until plaque is attened and the
Capillaries—smallest vessels and the place where the
r
exchange of gasses and nutrients takes place, connect
the arterioles and the venules
Venules—smaller divisions of the veins
r
Veins—carry blood back to the heart from the venules
r
There are two subdivisions of the circulatory system,
one that delivers blood to the lungs, the pulmonary circuit, and the systemic circuit that carries blood to the
rest of the body tissues.
Plaque
expanded:
catheter
removed
Dashed lines
indicate
old plaque
thickness
heart disease.
Pulmonary Circuit
C
O
G
THE CIRCULATORY
SYSTEM
Now that we have examined the heart, its function,
and disorders, let’s take a look at the blood vessels that
carry the blood throughout the body. The blood vessels
include the following:
Arteries—carry blood away from the heart
r
Arterioles—smaller divisions of the arteries
r
This circulatory system delivers blood to the lungs to
become oxygenated and leave some carbon dioxide,
which will be eliminated from the body through respirations. Blood that has returned to the heart from
the body is low in oxygen and will leave the right
ventricle to be transported to the lungs in the pulmonary arteries. This is the only place where arteries that
always carry blood away from the heart are carrying
deoxygenated blood. In the lungs, the gas exchange
takes place and the blood returns to the heart in the
160 Section II Anatomy and Physiology
pulmonary veins, the only veins in the body that carry
oxygenated blood.
Systemic Circuit
This subdivision of the circulatory system supplies
oxygen and nutrients to the body tissues and carries
carbon dioxide and waste products away from the tissues. Blood leaves the heart in the largest artery, the
aorta. It travels throughout the body from the arteries to the arterioles, through the capillaries, into the
venules and then the veins. Blood nally returns to the
heart in the superior vena cava, from the upper body,
and the inferior vena cava from the lower part of the
body. See Figure 8-5, which shows the how the closed
circuit of the cardiovascular system keeps blood owing in one direction. You can also see how the oxygenated blood is supplied by the lungs and sent to the
body to give up the oxygen, becoming deoxygenated
blood.
The Arteries
The arteries have thicker walls to carry the blood under
greater pressure as it leaves the heart and starts the process of circulation. The walls of the arteries are elastic making them easier to enlarge to accommodate the
Pulmonary capillaries
Pulmonary
arterioles
Pulmonary
arteries
Pulmonic
valve
Right
ventricle
Tricuspid
valve
Right
atrium
Superior
and inferior
venae cavae
Systemic
veins
Systemic
venules
Systemic capillaries
Figure 8-5 Circulation throughout the body. (Reprinted
from Cohen BJ. Memmler’s The Human Body in Health and
Disease. 13th ed. Philadelphia, PA: Wolters Kluwer; 2014.)
Pulmonary
veins
Systemic
arteries
Pulmonar
Left
atrium
Mitral
valve
Left
ventricle
Aortic
valve
Aorta
Systemic
arterioles
y
venules
changes in pressure. The middle layer of the arteries is
made up of smooth muscle, which is involuntary, working without conscious control. The blood ows from
the arteries into the arterioles and then to the capillaries.
The Capillaries
The capillaries connect the arterioles and the venules.
They are only wide enough for a single blood cell to pass
through. They are the thinnest with only one cell layer.
This is the place where the gas and nutrient exchange
takes place.
The Veins
The venules carry blood from the capillaries to the veins.
When compared to the arteries, the veins have thinner
walls. They also have one-way valves only allowing
blood to continue to ow in one direction. The pressure
within the veins is less than in the arteries. The valves
help push the blood forward so it does not ow back.
Table 8-2 lists the major arteries and veins of the body
and Table 8-3 lists the major veins. See Figure 8-6, which
shows the major arteries and veins of the body.
Blood Flow
The blood vessels are able to change their internal
diameter to regulate the blood ow. Vasodilation is the
increase in the diameter allowing more blood to ow
through, and vasoconstriction is a decrease in the diameter causing the blood ow to decrease. These changes
are regulated by the autonomic nervous system from
signals sent by the medulla of the brainstem. When
the blood leaves the heart in the arteries, it is pushed
through the circulatory system under greater pressure
than the amount found in the veins. The veins need help
pushing the blood through the system back to the heart.
The body relies on gravity to assist with some of this
function. The contraction of the skeletal muscles also
aids in pushing the blood through the veins. As mentioned earlier, the veins have valves that also keep the
blood owing without backow.
Another mechanism that helps venous blood ow is
breathing. The movement of the diaphragm helps the
blood in the abdomen and thorax to return to the heart.
Physical inactivity can cause blood to pool in the lower
extremities. The arteries are used to measure the pulse
rate. When an artery is pressed against a bone, a pulse
is felt. The most common site for taking a pulse is the
radial artery located on the thumb side of the posterior
wrist. The pulse is counted for a full minute and should
be between 60 and 80 beats per minute in a healthy
adult at rest. The quality of the pulse is also noted. It
can be strong or weak and may be regular or irregular
in rhythm. Blood pressure is also measured as the force
exerted by the blood against the walls of the arteries.