Deck 17: Cardiac Function

Question 1

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.

Answer 1

altering myosin affinity for actin-binding sites.

Question 2

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

Answer 2

ADP and phosphate

Question 3

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.

Answer 3

binds troponin, causing actin-binding sites to be exposed.

Question 4

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 5

Which is a true statement about the affect of the Frank-Starling law on 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 6

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 b receptors on the cell membrane.
D) inhibits voltage-gated sodium channels in the membrane.

Question 7

Which is true about 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 8

While caring for a geriatric patient, the changes in the heart that may be expected include

A) increased oxygen consumption.
B) increased coronary artery blood flow.
C) decreased response to an elevated heart rate.
D) cardiomyopathy.

Question 9

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.

Question 10

Which is true about blood flow from the atria?

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

At very high heart rates, cardiac output

A) decreases.
B) increases.
C) stays the same.
D) reverses.

Question 12

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.

Question 13

Which proteins are associated with the thin filament in the cardiac muscle?

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

Question 14

Automatic pacemaker cells spontaneously depolarize, because

A) leak channels (If) 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 15

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 16

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 17

The v wave of an atrial pressure tracing corresponds to

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

Question 18

Which physiologic change increases cardiac work but does not enhance cardiac output?

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

Question 19

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

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

Question 20

A vessel that normally contains desaturated (venous)blood is the

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

Question 21

The R wave is responsible for ________ depolarization.

Question 22

A requirement for rhythmicity is that the cell membrane has channels that automatically open during phase ________.

Question 23

Echocardiograms are used to help diagnose

A) heart enlargement.
B) valvular disorders.
C) cardiac tumors.
D) left ventricular motion abnormalities.
E) collection of fluid in lung bases.

Question 24

A standard ECG has ________ leads.

Question 25

Electrical currents that travel through the heart are called vectors because they include

A) direction.
B) polarity.
C) magnitude.
D) vascularity.
E) ionic waves.

Question 26

The major wave complexes of an ECG include the

A) P wave.
B) B wave.
C) TUV complex.
D) QRS complex.
E) T wave.

Question 27

The major factors that influence stroke volume are

A) pre-ejection.
B) preload.
C) resistance.
D) contractility.
E) afterload.