C H A P T E R 4 2
Introduction to the cardiovascular system
655
C H E C K Y O U R U N D E R S T A N D I N G
Answers to the questions in this chapter can be found in
Appendix A at the back of this book.
MULTIPLE CHOICE
Select the best answer to the following.
1.
When describing heart valves to a group of students,
which of the following would the instructor include?
a.
The closing of the AV valves is what is
responsible for heart sounds.
b.
Small muscles attached to the AV valves are
responsible for opening and closing the valves.
c.
The aortic valve opens when the pressure in the
left ventricle becomes greater than the aortic
pressure.
d.
The valves leading to the great vessels are called
the cuspid valves.
2.
In the heart:
a.
the ventricles will not contract unless they are
stimulated by action potentials arising from the
SA node.
b.
fibrillation of the atria will cause blood pressure
to fall to zero.
c.
spontaneous depolarisation of the muscle
membrane can occur in the absence of nerve
stimulation.
d.
the muscle can continue to contract for a long
period of time in the absence of oxygen.
3.
The activity of the heart depends on both the
inherent properties of the cardiac muscle cells and
the activity of the autonomic nerves to the heart.
Therefore:
a.
cutting all of the autonomic nerves to the heart
produces a decrease in heart rate.
b.
blocking the parasympathetic nerves to the heart
decreases the heart rate.
c.
stimulating the sympathetic nerves to the heart
increases the time available to fill the ventricles
during diastole.
d.
the heart rate will increase in cases of
dehydration, which leads to low cardiac output.
4.
A person with a transplanted heart has no nerve
connections to the transplanted heart. In such an
individual, one would expect to find:
a.
a slower-than-normal resting heart rate.
b.
atria that contract at a different rate than
ventricles.
c.
an increase in heart rate during emotional stress.
d.
inability to exercise because there is no way to
increase heart rate.
5.
The baroreceptors in the carotid sinus and aortic
arch:
a.
are in appropriate position to protect the brain.
b.
decrease the frequency of impulses sent to the
cardiovascular centre when arterial blood pressure
is increased.
c.
monitor the magnitude of concentration of
oxygen in the vessels.
d.
react to high levels of carbon dioxide in the aorta
or carotid.
6.
Cardiac cells differ from skeletal muscle cells in that:
a.
they contain actin and myosin.
b.
they possess automaticity and conductivity.
c.
calcium must be present for muscle contraction to
occur.
d.
they do not require oxygen to survive.
7.
Clinically, dysrhythmias or arrhythmias cause:
a.
altered cardiac output that could affect all cells.
b.
changes in capillary filling pressures.
c.
alterations in osmotic pressure.
d.
valvular dysfunction.
8.
A person is brought to the emergency room with a
suspected myocardial infarction. The person is very
upset because he had just had an ECG in his doctor’s
office and it was fine. The explanation of this
common phenomenon would include the fact that:
a.
the ECG only reflects changes in cardiac output.
b.
the ECG is not a very accurate test.
c.
the ECG only measures the flow of electrical
current through the heart.
d.
the ECG is not related to the heart problems.
9.
Blood flow to the myocardium differs from blood
flow to the rest of the cells of the body in that:
a.
blood perfuses the myocardium during systole.
b.
blood flow is determined by many local factors,
including buildup of acid.
c.
blood perfuses the myocardium during diastole.
d.
oxygenated blood flows to the myocardium via
veins.
MULTIPLE RESPONSE
Select all that apply.
1.
During diastole, which of the following would occur?
a.
opening of the atrioventricular valves
b.
relaxation of the myocardial muscle
c.
flow of blood from the atria to the ventricles
d.
contraction of the ventricles
e.
closing of the semilunar valves
f.
filling of the coronary arteries
