Chapter 14 review questions

Question 1

List three functions of the cardiovascular system.

Answer 1

transport of materials entering and leaving the body, defense, and cell-to-cell communication

Question 1

What contributions to understanding the cardiovascular system did each of the following people make?
A.William Harvey
B. Otto Frank and Ernest Starling
C. Marcello Malpighi

Answer 1

(a) first European to describe the closed circulatory system, (b) described the relationship between ventricular muscle stretch and force of contraction, (c) described capillaries

Question 2

Put the following structures in the order in which blood passes through them, starting and ending with the left ventricle:
a. left ventricle
b. systemic veins
c. pulmonary circulation
d. systemic arteries
e. aorta
f. right ventricle

Answer 2

a—e—d—b—f—c—a

Question 3

The primary factor causing blood to flow through the body is a(n) __________gradient. In humans, the value of this gradient is highest at the ________ and in the ________. It is lowest in the _______. In a system in which fluid is flowing, pressure decreases over distance because of __________.

Answer 3

pressure, left ventricle, aorta, right atrium, friction

Question 4

If vasodilation occurs in a blood vessel, pressure (increases/decreases).

Answer 4

decreases

Question 5

The specialized cell junctions between myocardial cells are called . These areas contain that allow rapid conduction of electrical signals.

Answer 5

intercalated disks, gap junctions

Question 6

Trace an action potential from the SA node through the conducting system of the heart.

Answer 6

SA node to internodal pathways to AV node to bundle of His (left and right branches) to Purkinje fibers to ventricular myocardium

Question 7

Distinguish between the two members of each of the following pairs:
a. end-systolic volume and end-diastolic volume
b. sympathetic and parasympathetic control of heart rate
c. diastole and systole
d. systemic and pulmonary circulation
e. AV node and SA node

Answer 7

(a) ESV—volume of blood in ventricle at end of contraction; EDV—volume of blood in the ventricle at beginning of contraction, (b)Sympathetic increases heart rate; parasympathetic decreases heart rate. (c) diastole = relaxation; systole = contraction, (d) Pulmonary goes to the lungs; systemic goes to rest of body. (e) SA node is the (atrial) pacemaker; AV node transmits signals from atria to ventricles.

Question 8

Match the descriptions with the correct anatomic term(s). Not all terms are used and terms may be used more than once. Give a definition for the unused terms.

a. tough membranous sac that encases the heart
b. valve between ventricle and a main artery
c. a vessel that carries blood away from the heart
d. lower chamber of the heart
e. valve between left atrium and left ventricle
f. primary artery of the systemic circulation
g. muscular layer of the heart
h. narrow end of the heart; points downward
i. valve with papillary muscles
j. the upper chambers of the heart

1. aorta
2. apex
3. artery
4. atria
5. atrium
6. AV valve
7. base
8. bicuspid valve
9. endothelium
10. myocardium
11. pericardium
12. semilunar valve
13. tricuspid valve
14. ventricle

Answer 8

(a) 11, (b) 12, (c) 3, (d) 14, (e) 8, (f) 1, (g) 10, (h) 2, (i) 6, (j) 4

Question 9

What events cause the two principal heart sounds?

Answer 9

Vibrations from AV closure cause the “lub” sound and from semilunar valve closure cause the “dup” sound.

Question 10

What is the proper term for each of the following?
number of heart contractions per minute
a. volume of blood in the ventricle before the heart contracts
b. volume of blood that enters the aorta with each contraction
c. volume of blood that leaves the heart in 1 minute
e. volume of blood in the entire body

Answer 10

(a) heart rate, (b) end-diastolic volume, (c) stroke volume, (d) cardiac output, (e) blood volume

Question 11

Level Two Reviewing Concepts:

List the events of the cardiac cycle in sequence, beginning with atrial and ventricular diastole. Note when valves open and close. Describe what happens to pressure and blood flow in each chamber at each step of the cycle.

Answer 11

See Figs. 14.18 and 14.19.

Question 12

Mapping exercise:
Create a map showing blood flow through the heart and body. Label as many structures as you can.
Create a map for control of cardiac output using the following terms. You may add additional terms.
ACh
adrenal medulla
autorhythmic cells
β1-receptor
Ca2+
Ca2+-induced Ca2+
cardiac output
contractile myocardium
contractility
force of contraction
heart rate
length-tension relationship
muscarinic receptor
norepinephrine
parasympathetic neurons
respiratory pump
skeletal muscle pump
stroke volume
sympathetic neurons
venous return

Answer 12

(a) Refer to Fig. 14.1. (b) Use Figs. 14.20 and 14.23 as a starting point for a map.

Question 13

Compare and contrast the structure of a cardiac muscle cell with that of a skeletal muscle cell. What unique properties of cardiac muscle are essential to its function?

Answer 13

See Tbl. 12.3. Cardiac muscle has strong cell-to-cell junctions, gap junctions for electrical conduction, and the modification of some muscle cells into autorhythmic cells.

Question 14

Explain why contractions in cardiac muscle cannot sum or exhibit tetanus.

Answer 14

The long refractory period prevents a new action potential until the heart muscle has relaxed.

Question 15

Correlate the waves of an ECG with mechanical events in the atria and ventricles. Why are there only three electrical events but four mechanical events?

Answer 15

See Fig. 14.17. Atrial relaxation and ventricular contraction overlap during the QRS complex.

Question 16

Match the following ion movements with the appropriate phrase. More than one ion movement may apply to a single phrase. Some choices may not be used.

a. slow rising phase of autorhythmic cells
b. plateau phase of contractile cells
c. rapid rising phase of contractile cells
d. rapid rising phase of autorhythmic cells
e. rapid falling phase of contractile cells
f. falling phase of autorhythmic cells
g. cardiac muscle contraction
h. cardiac muscle relaxation

1. from ECF to ICF
2. from ICF to ECF
3. from ECF to ICF
4. from ICF to ECF
5. from ECF to ICF
6. from ICF to ECF

Answer 16

(a) 3, 5 in the last part; (b) 5; (c) 3; (d) 5; (e) 2; (f) 2; (g) 5; (h) 6

Question 17

List and briefly explain four types of information that an ECG provides about the heart.

Answer 17

Heart rate, heart rhythm (regular or irregular), conduction velocity, and the electrical condition of heart tissue. An ECG does not give any direct information about force of contraction.

Question 18

Define inotropic effect. Name two drugs that have a positive inotropic effect on the heart.

Answer 18

An effect on force of contraction. Norepinephrine and cardiac glycosides

Question 19

Level three:
Two drugs used to reduce cardiac output are calcium channel blockers and beta (receptor) blockers. What effect do these drugshave on the heart that explains how they decrease cardiac output?

Answer 19

Calcium channel blockers slow heart rate by blocking Ca2+ entry and decrease the force of contraction by decreasing Ca2+-induced Ca2+ release. Beta-blockers decrease the effect of norepinephrine and epinephrine, preventing increased heart rate and force of contraction.

Question 20

Police Captain Jeffers has suffered a myocardial infarction.
a. Explain to his (nonmedically oriented) family what has happened to his heart.
b. When you analyzed his ECG, you referred to several different leads, such as lead I and lead III. What are leads?
c. Why is it possible to record an ECG on the body surface without direct access to the heart?

Answer 20

(a) His heart muscle has been damaged by lack of oxygen and the cells are unable to contract as strongly. Thus, less blood is being pumped out of the ventricle each time the heart contracts. (b) Leads are recording electrodes placed on the surface of the body to measure electrical activity. (c) Leads are effective because electricity is conducted through body fluids to the skin surface.

Question 21

What might cause a longer-than-normal PR interval in an ECG?

Answer 21

A conduction problem at the AV node or in the ventricular conduction system might cause a long PR interval.

Question 22

The following paragraph is a summary of a newspaper article:

A new treatment for atrial fibrillation due to an excessively rapid rate at the SA node involves a high-voltage electrical pulse administered to the AV node to destroy its autorhythmic cells. A ventricular pacemaker is then implanted in the patient.

Briefly explain the physiological rationale for this treatment. Why is a rapid atrial depolarization rate dangerous? Why is the AV node destroyed in this procedure? Why must a pacemaker be implanted?

Answer 22

Destroying the AV node will prevent rapid atrial signals from being passed to the ventricles. A ventricular pacemaker is implanted so that the ventricles have an electrical signal telling them to contract at an appropriate rate. Rapid atrial depolarization rate is dangerous because if the rate is too fast, only some action potentials will initiate contractions due to the refractory period of muscle. This can cause an arrhythmia.