Pathophysiology: Chapter 32: Structure and Function of the Cardiovascular and Lymphatic Systems

Question 1

Which statement does not accurately describe the pericardium?
a. The pericardium is a double-walled membranous sac that encloses the heart.
b. It is made up of connective tissue and a surface layer of squamous cells.
c. The pericardium protects the heart against infection and inflammation from the
lungs and pleural space.
d. It contains pain and mechanoreceptors that can elicit reflex changes in blood
pressure and heart rate.

Answer 1

ANS: B
The pericardium is made up of a surface layer of mesothelium over a thin layer of
connective tissue. The remaining options accurately describe the pericardium.

Question 2

Which cardiac chamber has the thinnest wall and why?
a. The right and left atria; they are low-pressure chambers that serve as storage units
and conduits for blood.
b. The right and left atria; they are not directly involved in the preload, contractility,
or afterload of the heart.
c. The left ventricle; the mean pressure of blood coming into this ventricle is from the
lung, which has a low pressure.
d. The right ventricle; it pumps blood into the pulmonary capillaries, which have a
lower pressure compared with the systemic circulation.

Answer 2

ANS: A
The two atria have the thinnest walls because they are low-pressure chambers that serve as
storage units and conduits for blood that is emptied into the ventricles. This selection is the
only option that correctly identifies which heart chambers have the thinnest walls and why
that helps cardiac function.

Question 3

Which chamber of the heart endures the highest pressures?

a. Right atrium c. Left ventricle
b. Left atrium d. Right ventricle

Answer 3

ANS: C

Pressure is greatest in the systemic circulation, driven by the left ventricle.

Question 4

What is the process that ensures mitral and tricuspid valve closure after the ventricles are
filled with blood?
a. Chordae tendineae relax, which allows the valves to close.
b. Increased pressure in the ventricles pushes the valves to close.
c. Trabeculae carneae contract, which pulls the valves closed.
d. Reduced pressure in the atria creates a negative pressure that pulls the valves
closed.

Answer 4

ANS: B
During ventricular relaxation, the two atrioventricular valves open and blood flows from
the higher pressure atria to the relaxed ventricles. With increasing ventricular pressure,
these valves close and prevent backflow into the atria as the ventricles contract. This
selection is the only option that correctly identifies the process that ensures closing of the
mitral and tricuspid valves.

Question 5

Regarding the heart’s valves, what is a function of the papillary muscles?

a. The papillary muscles close the semilunar valve.
b. These muscles prevent backward expulsion of the atrioventricular valve.
c. They close the atrioventricular valve.
d. The papillary muscles open the semilunar valve.

Answer 5

ANS: B
The papillary muscles are extensions of the myocardium that pull the cusps together and
downward at the onset of ventricular contraction, thus preventing their backward
expulsion into the atria. This selection is the only option that correctly describes the
function of the papillary muscles.

Question 6

During the cardiac cycle, why do the aortic and pulmonic valves close after the ventricles
relax?
a. Papillary muscles relax, which allows the valves to close.
b. Chordae tendineae contract, which pulls the valves closed.
c. Reduced pressure in the ventricles creates a negative pressure, which pulls the
valves closed.
d. Blood fills the cusps of the valves and causes the edges to merge, closing the
valves.

Answer 6

ANS: D
When the ventricles relax, blood fills the cusps and causes their free edges to meet in the
middle of the vessel, closing the valve and preventing any backflow. This selection is the
only option that accurately explains why the aortic and pulmonic valves close after the
ventricles contract.

Question 7

Oxygenated blood flows through which vessel?

a. Superior vena cava c. Pulmonary artery
b. Pulmonary veins d. Coronary veins

Answer 7

ANS: B
Only the four pulmonary veins, two from the right lung and two from the left lung, carry
oxygenated blood from the lungs to the left side of the heart.

Question 8

The significance of the atrial kick is that it affects the contraction of the:

a. Right atria, which is necessary to open the tricuspid valve.
b. Right atria, which is necessary to increase the blood volume from the vena cava.
c. Left atria, which increases the blood volume into the ventricle.
d. Left atria, that is necessary to open the mitral valve.

Answer 8

ANS: C
Left atrial contraction, the atrial kick, provides a significant increase of blood to the left
ventricle.

Question 9

Occlusion of the left anterior descending artery during a myocardial infarction would
interrupt blood supply to which structures?
a. Left and right ventricles and much of the interventricular septum
b. Left atrium and the lateral wall of the left ventricle
c. Upper right ventricle, right marginal branch, and right ventricle to the apex
d. Posterior interventricular sulcus and the smaller branches of both ventricles

Answer 9

ANS: A
The left anterior descending artery (LAD), also called the anterior interventricular artery,
delivers blood to portions of the left and right ventricles and much of the interventricular
septum. This selection is the only option affected by the occlusion described.

Question 10

Occlusion of the circumflex artery during a myocardial infarction would interrupt blood
supply to which area?
a. Left and right ventricles and much of the interventricular septum
b. Posterior interventricular sulcus and the smaller branches of both ventricles
c. Upper right ventricle, right marginal branch, and right ventricle to the apex
d. Left atrium and the lateral wall of the left ventricle

Answer 10

ANS: D
The circumflex artery supplies blood to the left atrium and the lateral wall of the left
ventricle. The circumflex artery often branches to the posterior surfaces of the left atrium
n described.and left ventricle. This selection is the only option affected by the occlusion

Question 11

The coronary ostia are located in the:

a. Left ventricle c. Coronary sinus
b. Aortic valve d. Aorta

Answer 11

ANS: D

Coronary arteries receive blood through openings in the aorta, called the coronary ostia.

Question 12

The coronary sinus empties into which cardiac structure?
a. Right atrium c. Superior vena cava
b. Left atrium d. Aorta
e vein called the coronary sinus.

Answer 12

ANS: A
The cardiac veins empty only into the right atrium through another ostium, the opening of
a large vein called the coronary sinus.

Question 13

What is the ratio of coronary capillaries to cardiac muscle cells?

a. 1:1 (one capillary per one muscle cell)
b. 1:2 (one capillary per two muscle cells)
c. 1:4 (one capillary per four muscle cells)
d. 1:10 (one capillary per ten muscle cells)

Answer 13

ANS: A
The heart has an extensive capillary network, with approximately 3300 capillaries per
square millimeter (ca/mm2) or approximately one capillary per one muscle cell (muscle
fiber).

Question 14

During the cardiac cycle, which structure directly delivers action potential to the
ventricular myocardium?
a. Sinoatrial (SA) node c. Purkinje fibers
b. Atrioventricular (AV) node d. Bundle branches

Answer 14

ANS: C
Each cardiac action potential travels from the SA node to the AV node to the bundle of His
(AV bundle), through the bundle branches, and finally to the Purkinje fibers and the
ventricular myocardium, where the impulse is stopped. The refractory period of cells that
have just been polarized prevents the impulse from reversing its path. The refractory
period ensures that diastole (relaxation) will occur, thereby completing the cardiac cycle.
This selection is the only option that accurately describes the structure that delivers the
action potential directly to the myocardium.

Question 15

What causes depolarization of a cardiac muscle cell to occur?

a. Decrease in the permeability of the cell membrane to potassium
b. Rapid movement of sodium into the cell
c. Decrease in the movement of sodium out of the cell
d. Rapid movement of calcium out of the cell

Answer 15

ANS: B
Phase 0 consists of depolarization, which lasts 1 to 2 milliseconds (ms) and represents
rapid sodium entry into the cell. This selection is the only option that accurately describes
the cause of cardiac muscle cell depolarization.

Question 16

Which event occurs during phase 1 of the normal myocardial cell depolarization and
repolarization?
a. Repolarization when potassium moves out of the cells
b. Repolarization when sodium rapidly enters into the cells
c. Early repolarization when sodium slowly enters the cells
d. Early repolarization when calcium slowly enters the cells

Answer 16

ANS: D
Phase 1 is early repolarization and the only time during which calcium slowly enters the
cell.

Question 17

Which phase of the normal myocardial cell depolarization and repolarization correlates
with diastole?
a. Phase 1 c. Phase 3
b. Phase 2 d. Phase 4

Answer 17

ANS: D
Potassium is moved out of the cell during phase 3, with a return to resting membrane
potential only in phase 4. The time between action potentials corresponds to diastole.

Question 18

In the normal electrocardiogram, what does the PR interval represent?
a. Atrial depolarization
b. Ventricular depolarization
c. Atrial activation to onset of ventricular activity
d. Electrical systole of the ventricles
ANS: C
The PR interval is a measure of time from the onset of atrial activation to the onset of
ventricular activation; it normally ranges from 0.12 to 0.20 second. The PR interval
represents the time necessary to travel from the sinus node through the atrium, the
atrioventricular (AV) node, and the His–Purkinje system to activate ventricular myocardial
cells. This selection is the only option that accurately describes the PR interval.

Answer 18

ANS: C
The PR interval is a measure of time from the onset of atrial activation to the onset of
ventricular activation; it normally ranges from 0.12 to 0.20 second. The PR interval
represents the time necessary to travel from the sinus node through the atrium, the
atrioventricular (AV) node, and the His–Purkinje system to activate ventricular myocardial
cells. This selection is the only option that accurately describes the PR interval.

Question 19

The cardiac electrical impulse normally begins spontaneously in the sinoatrial (SA) node
because it:
a. Has a superior location in the right atrium.
b. Is the only area of the heart capable of spontaneous depolarization.
c. Has rich sympathetic innervation via the vagus nerve.
d. Depolarizes more rapidly than other automatic cells of the heart.

Answer 19

ANS: D
The electrical impulse normally begins in the SA node because its cells depolarize more
rapidly than other automatic cells. This selection is the only option that accurately explains
why cardiac electrical impulses normally begin spontaneously in the SA node.

Question 20

What period follows depolarization of the myocardium and represents a period during
which no new cardiac potential can be propagated?
a. Refractory c. Threshold
b. Hyperpolarization d. Sinoatrial (SA)

Answer 20

ANS: A
During the refractory period, no new cardiac action potential can be initiated by a
stimulus. This selection is the only option that accurately identifies the period described in
the question.

Question 21

Which complex (wave) represents the sum of all ventricular muscle cell depolarizations?

a. PRS c. QT interval
b. QRS d. P

Answer 21

ANS: B

Only the QRS complex represents the sum of all ventricular muscle cell depolarizations.

Question 22

What can shorten the conduction time of action potential through the atrioventricular (AV)
node?
a. Parasympathetic nervous system 
b. Catecholamines
c. Vagal stimulation 
d. Sinoatrial node (SA)

Answer 22

ANS: B
Catecholamines speed the heart rate, shorten the conduction time through the AV node,
and increase the rhythmicity of the AV pacemaker fibers. This selection is the only option
that can perform that function.

Question 23

If the sinoatrial (SA) node fails, then at what rate (depolarizations per minute) can the
atrioventricular (AV) node depolarize?
a. 60 to 70 c. 30 to 40
b. 40 to 60 d. 10 to 20

Answer 23

ANS: B
If the SA node is damaged, then the AV node will become the heart’s pacemaker at a rate
of approximately 40 to 60 spontaneous depolarizations per minute.

Question 24

What is the effect of epinephrine on Beta 3 receptors on the heart?

a. Decreases coronary blood flow.
b. Supplements the effects of both Beta 1 and Beta 2 receptors.
c. Increases the strength of myocardial contraction.
d. Prevents overstimulation of the heart by the sympathetic nervous system.

Answer 24

ANS: D

Beta 3 receptors are found in the myocardium and coronary vessels. In the heart, stimulation of
these receptors opposes the effects of beta 1- and Beta 2-receptor stimulation and negative
inotropic effect. Thus beta 3 receptors may provide a safety mechanism that decreases
myocardial contractility to prevent overstimulation of the heart by the sympathetic nervous
system. This selection is the only option that accurately describes the effect of epinephrine
on beta 2 receptors on the heart.

Question 25

Where in the heart are the receptors for neurotransmitters located?

a. Semilunar and atrioventricular (AV) valves
b. Endocardium and sinoatrial (SA) node
c. Myocardium and coronary vessels
d. Epicardium and AV node

Answer 25

ANS: C
Sympathetic neural stimulation of the myocardium and coronary vessels depends on the
presence of adrenergic receptors, which specifically bind with neurotransmitters of the
sympathetic nervous system. The Beta 1 receptors are found mostly in the heart, specifically
the conduction system (AV and SA nodes, Purkinje fibers) and the atrial and ventricular
myocardium, whereas the Beta 2 receptors are found in the heart and also on vascular smooth
muscle. Beta 3 receptors are also found in the myocardium and coronary vessels. This
selection is the only option that accurately identifies the location of the receptors for
neurotransmitters.

Question 26

What enables electrical impulses to travel in a continuous cell-to-cell fashion in
myocardial cells?
a. Sarcolemma sclerotic plaques 
b. Intercalated disks
c. Trabeculae carneae
d. Bachmann bundles

Answer 26

ANS: B
Only intercalated disks, thickened portions of the sarcolemma, enable electrical impulses
to spread quickly in a continuous cell-to-cell (syncytial) fashion.

Question 27

Within a physiologic range, what does an increase in left ventricular end-diastolic volume

(preload) result in?
a. Increase in force of contraction
b. Decrease in refractory time
c. Increase in afterload
d. Decrease in repolarization

Answer 27

ANS: A
This concept is expressed in the Frank-Starling law; the cardiac muscle, like other
muscles, increases its strength of contraction when it is stretched. This selection is the only
option that accurately describes the result of an increase in preload.

Question 28

As stated in the Frank-Starling law, a direct relationship exists between the _____ of the
blood in the heart at the end of diastole and the _____ of contraction during the next
systole.
a. Pressure; force
b. Volume; strength
c. Viscosity; force
d. Viscosity; strength

Answer 28

ANS: B
As stated in the Frank-Starling law, the volume of blood in the heart at the end of diastole
(the length of its muscle fibers) is directly related to the force (strength) of contraction
during the next systole. This selection is the only option that accurately describes the
relationship associated with the Frank-Starling law.

Question 29

Pressure in the left ventricle must exceed pressure in which structure before the left
ventricle can eject blood?
a. Superior vena cava 
b. Aorta 
c. Inferior vena cava
d. Pulmonary veins

Answer 29

ANS: B
Pressure in the ventricle must exceed aortic pressure before blood can be pumped out
during systole. The aorta is the only structure in which pressure must be less than the
amount of blood in the left ventricle for ejection to occur.

Question 30

Continuous increases in left ventricular filing pressures result in which disorder?

a. Mitral regurgitation
b. Mitral stenosis
c. Pulmonary edema
d. Jugular vein distention

Answer 30

ANS: C
Pressure changes are important because increased left ventricular filling pressures back up
into the pulmonary circulation, where they force plasma out through vessel walls, causing
fluid to accumulate in lung tissues (pulmonary edema). This selection is the only option
that accurately identifies the disorder described in the question.

Question 31

When the volume of blood in the ventricle at the end of diastole increases, the force of the
myocardial contraction during the next systole will also increase, which is an example of
which law or theory about the heart?
a. Laplace’s law
b. Poiseuille law
c. Cross-bridge theory
d. Frank-Starling law

Answer 31

ANS: D
This concept is expressed only in the Frank-Starling law; the cardiac muscle, like other
muscles, increases its strength of contraction when it is stretched.

Question 32

The resting heart rate in a healthy person is primarily under the control of which nervous
system?
a. Sympathetic 
b. Parasympathetic
c. Somatic 
d. Spinal

Answer 32

ANS: B
The resting heart rate in healthy individuals is primarily under the control of
parasympathetic stimulation. This selection is the only option that accurately identifies the
nervous system responsible for the healthy resting heart.

Question 33

The Bainbridge reflex is thought to be initiated by sensory neurons in which cardiac
location?
a. Atria 
b. Aorta
c. Sinoatrial (SA) node 
d. Ventricles

Answer 33

ANS: A
The Bainbridge reflex causes changes in the heart rate after intravenous infusions of blood
or other fluid. The changes in heart rate are thought to be caused by a reflex mediated by
volume receptors found only in the atria that are innervated by the vagus nerve.

Question 34

After the baroreceptor reflex is stimulated, the resulting impulse is transmitted from the
carotid artery by which sequence of events?
a. Vagus nerve to the medulla to increase parasympathetic activity and to decrease
sympathetic activity
b. Glossopharyngeal cranial nerve through the vagus nerve to the medulla to increase
sympathetic activity and to decrease parasympathetic activity
c. Glossopharyngeal cranial nerve through the vagus nerve to the medulla to increase
parasympathetic activity and to decrease sympathetic activity
d. Glossopharyngeal cranial nerve through the vagus nerve to the hypothalamus to
increase parasympathetic activity and to decrease sympathetic activity

Answer 34

ANS: C
Neural impulses are transmitted over the glossopharyngeal nerve (ninth cranial nerve)
from the carotid artery and through the vagus nerve from the aorta to the cardiovascular
control centers in the medulla. These centers initiate an increase in parasympathetic
activity and a decrease in sympathetic activity, causing blood vessels to dilate and the
heart rate to decrease. This selection is the only option that accurately describes the correct
sequence of events asked for in the question.

Question 35

Reflex control of total cardiac output and total peripheral resistance is controlled by what
mechanism?
a. Parasympathetic stimulation of the heart, arterioles, and veins
b. Sympathetic stimulation of the heart, arterioles, and veins
c. Autonomic control of the heart only
d. Somatic control of the heart, arterioles, and veins

Answer 35

ANS: B
Reflex control of total cardiac output and peripheral resistance includes (1) sympathetic
stimulation of the heart, arterioles, and veins; and (2) parasympathetic stimulation of the
heart only. Neither autonomic nor somatic controls are involved in this process.

Question 36

What is the most important negative inotropic agent?

a. Norepinephrine
b. Epinephrine
c. Acetylcholine
d. Dopamine

Answer 36

ANS: C
Chemicals affecting contractility are called inotropic agents. The most important negative
inotropic agent is acetylcholine released from the vagus nerve. The most important
positive inotropic agents produced by the body are norepinephrine released from the
sympathetic nerves that supply the heart and epinephrine released by the adrenal cortex.
Other positive inotropes include thyroid hormone and dopamine. Many medications have
positive or negative inotropic properties that can have profound effects on cardiac
function. This selection is the only option that accurately identifies the regulation that is
involved in the described process.

Question 37

The right lymphatic duct drains into which structure?

a. Right subclavian artery
b. Right atrium
c. Right subclavian vein
d. Superior vena cava

Answer 37

ANS: C

The right lymphatic duct drains lymph only into the right subclavian vein.

Question 38

Where is the major cardiovascular center in the central nervous system?

a. Frontal lobe
b. Thalamus
c. Brainstem
d. Hypothalamus

Answer 38

ANS: C
The major cardiovascular control center is in the brainstem in the medulla with secondary
areas in the hypothalamus, the cerebral cortex, the thalamus, and the complex networks of
exciting or inhibiting interneurons (connecting neurons) throughout the brain. This
selection is the only option that accurately identifies the cardiovascular control center.

Question 39

What is an expected change in the cardiovascular system that occurs with aging?

a. Arterial stiffening
b. Decreased left ventricular wall tension
c. Decreased aortic wall thickness
d. Arteriosclerosis

Answer 39

ANS: A
Arterial stiffening occurs with aging even in the absence of clinical hypertension. Aging is
not responsible for the other conditions.

Question 40

What is the major determinant of the resistance that blood encounters as it flows through
the systemic circulation?
a. Volume of blood in the systemic circulation
b. Muscle layer of the metarterioles
c. Muscle layer of the arterioles
d. Force of ventricular contraction

Answer 40

ANS: C
Of the options available, only the thick, smooth muscle layer of the arterioles is a major
determinant of the resistance blood encounters as it flows through the systemic circulation.

Question 41

Which function of the cardiovascular system is often affected by ischemia?

a. Cardiac output (CO)
b. Stroke volume (SV)
c. Heart rate (HR)
d. Cardiac index (CI)

Answer 41

ANS: C
Common causes of an abnormal heart rate include ischemia, electrolyte imbalance, and
drug toxicity. The other options are related to vascular resistance changes.

Question 42

What physical sign is the result of turbulent blood flow through a vessel?

a. Increased blood pressure during periods of stress
b. Bounding pulse felt on palpation
c. Cyanosis observed on excretion
d. Murmur heard on auscultation

Answer 42

ANS: D
Where flow is obstructed, the vessel turns or blood flows over rough surfaces. The flow
becomes turbulent with whorls or eddy currents that produce noise, causing a murmur to
be heard on auscultation, such as occurs during blood pressure measurement with a
sphygomanometer. This selection is the only option that accurately identifies the physical
sign of turbulent vascular blood flow.

Question 43

What is the major effect of a calcium channel blocker such as verapamil on cardiac
contractions?
a. Increases the rate of cardiac contractions.
b. Decreases the strength of cardiac contractions.
c. Stabilizes the rhythm of cardiac contractions.
d. Stabilizes the vasodilation during cardiac contractions.

Answer 43

ANS: B
The L-type, or long-lasting, channels are the predominant type of calcium channels and are
the channels blocked by calcium channel–blocking drugs (verapamil, nifedipine,
diltiazem). The major effect of these medications is to decrease the strength of cardiac
contraction. This selection is the only option that accurately identifies the effect of a
calcium channel blocker on the cardiac contractions.

Question 44

An early diastole peak caused by filling of the atrium from peripheral veins is identified by
which intracardiac pressure?
a. A wave c. C wave
b. V wave d. X descent

Answer 44

ANS: B
The V wave is an early diastolic peak caused by the filling of the atrium from the
peripheral veins. This event is not identified by any of the other options.

Question 45

Which intracardiac pressure is generated by the atrial contraction?

a. A wave c. Y descent
b. C wave d. X descent

Answer 45

ANS: A
Atrial pressure curves are made up of only the A wave, which is generated by atrial
contraction.

Question 46

Which intracardiac pressure is produced because of the descent of the tricuspid valve ring
and by the ejection of blood from both ventricles?
a. V wave c. Y descent
b. C wave d. X descent

Answer 46

ANS: D
The X descent follows an A wave and is produced because of the descent of the tricuspid
valve ring and by the ejection of blood from both ventricles.