Deck 17: Cardiac Function

Question 1

The heart sound S₁ is produced when the atrioventricular valves close.

Answer 1

True

Question 2

Creatine phosphate is

A) a waste product of cellular metabolism.
B) synthesized when ATP levels are high.
C) enzymatically degraded to form creatine kinase.
D) an indicator of myocardial cell damage.

Answer 2

synthesized when ATP levels are high.

Question 3

The heart sound S₂ is due to closing of the aortic and pulmonic valves.

Answer 3

True

Question 4

Normally three coronary ostia are found in the aorta just distal to the aortic valve.

Question 5

The mitral valve

A) opens during ventricular systole.
B) is located between the right atrium and right ventricle.
C) has three valve leaflets.
D) allows blood to flow from the left atrium to the left ventricle.

Question 6

All of the following statements regarding cardiac muscle relaxation are correct except it

A) is an energy-requiring process.
B) is called luisotropy.
C) is inhibited by cAMP.
D) cannot be increased by current pharmacologic interventions.

Question 7

The v wave of an atrial pressure tracing corresponds to

A) atrial filling.
B) ventricular systole.
C) atrial systole.
D) mitral valve closure.

Question 8

Phase 0 of the cardiac muscle cell action potential is associated with _____ channels.

A) opening of slow calcium ion
B) opening of fast potassium ion
C) opening of fast sodium ion
D) closure of sodium leak

Question 9

The time between mitral valve closure and aortic valve opening is called the isovolumic contraction phase of the cardiac cycle.

Question 10

Blood flow through the coronary arteries

A) occurs primarily during systole because perfusion pressure is high.
B) is controlled primarily by the autonomic nervous system.
C) is increased with elevated right atrial pressure.
D) occurs primarily during ventricular diastole.

Question 11

The blood in the pulmonary veins has an oxygen saturation of about 75%.

Question 12

Calcium entry from the extracellular fluid into the myocardial cytoplasm is an energy-requiring process.

Question 13

A vessel that normally contains desaturated (venous) blood is

A) bronchial artery.
B) pulmonary artery.
C) pulmonary vein.
D) coronary artery.

Question 14

Most blood flow through the coronary arteries occurs during ventricular diastole.

Question 15

An increase in intracellular calcium ion results in myocardial contraction because calcium

A) activates membrane calcium pumps.
B) binds troponin, causing actin-binding sites to be exposed.
C) increases affinity of myosin for actin cross-bridge sites.
D) promotes ATP synthesis.

Question 16

Blood is transported from the right ventricle to the lungs by the

A) pulmonary veins.
B) aorta.
C) pulmonary artery.
D) bronchial arteries.

Question 17

During which phase of the cardiac cycle is the mitral valve normally open?

A) Atrial systole
B) Isovolumic contraction
C) Isovolumic relaxation
D) Ventricular ejection

Question 18

The principal determinant of heart rate is the baroreceptor reflex.

Question 19

Stroke volume is reduced when afterload is increased.

Question 20

The a wave on an atrial pressure tracing occurs during atrial systole.

Question 21

Cardiac myosin has a high affinity for actin when the myosin has what molecule(s) bound to it?

A) Calcium
B) ATP
C) ADP and phosphate
D) Creatine phosphate

Question 22

Which of the following proteins is not associated with the thin filament in the cardiac muscle?

A) Actin
B) Titin
C) Nebulin
D) Troponin

Question 23

Parasympathetic stimulation of the heart generally leads to a decrease in heart rate because acetylcholine

A) increases intracellular cAMP levels and opens calcium channels.
B) opens potassium channels allowing potassium ion efflux.
C) binds and blocks $\beta$ receptors on the cell membrane.
D) inhibits voltage-gated sodium channels in the membrane.

Question 24

Which of the following physiologic changes would increase cardiac work but not enhance cardiac output?

A) Increased preload
B) Increased heart rate
C) Increased contractility
D) Increased afterload

Question 25

In lead II of a normal electrocardiogram (ECG), the Q wave is a downward deflection resulting from _____ depolarization.

A) atrial
B) apical
C) lateral wall
D) septal

Question 26

Automatic pacemaker cells spontaneously depolarize because

A) leak channels (I_f) allow calcium and sodium ions into the cell.
B) they lack efficient sodium/potassium pumps.
C) voltage-sensitive sodium channels open spontaneously.
D) chloride leaks into the cell during rest.

Question 27

One role of ATP in cardiac muscle contraction is

A) providing energy to pump calcium into the cell.
B) inducing a conformational change in tropomyosin.
C) altering myosin affinity for actin-binding sites.
D) releasing sequestered calcium from the sarcoplasmic reticulum.

Question 28

Which of the following relationships is a statement about the Frank-Starling law of the heart?

A) Increased diastolic stretching of myocardial fibers produces increased stroke volume.
B) Sympathetic activation leads to increased myocardial contractility and heart rate.
C) An increase in heart chamber diameter increases myocardial wall tension.
D) An increase in coronary artery diameter results in less rapid coronary blood flow.

Question 29

Myocardial cells are connected by gap junctions enabling them to

A) all be stimulated simultaneously.
B) function as a coordinated syncytium.
C) be affected by the autonomic nervous system.
D) share ATP.