Question 1

Which of the following is an anticipated effect of increasing preload in the healthy heart?

Accepted Answer

A)  Decreased cardiac output 
B)  Decreased myocardial work 
C)  Increased stroke volume 
D)  Increased heart rate C

Question 2

What is the anticipated effect of vagal stimulation on the heart?

Accepted Answer

A)  It shortens the refractory period 
B)  It widens the QRS complex 
C)  It slows the heart rate 
D)  It increases the coronary blood supply C

Question 3

Mechanical activation of the heart occurs after electrical excitation because of the action of which of the following ions?

Accepted Answer

A)  Calcium 
B)  Phosphorus 
C)  Sodium 
D)  Potassium A

Question 4

Which of the following properties is unique to cardiac pacemaker cells?

Accepted Answer

A)  Automaticity 
B)  Rhythmicity 
C)  Conductivity 
D)  Refractoriness

Question 5

Vagal stimulation of the heart leads to

Accepted Answer

A)  bradycardia. 
B)  tachycardia. 
C)  ventricular arrhythmias. 
D)  atrial arrhythmias.

Question 6

The effective refractory period is when the heart cell

Accepted Answer

A)  may be stimulated by the atrioventricular node. 
B)  cannot respond to a stimulus. 
C)  can create a full action potential. 
D)  responds repetitively.

Question 7

Repolarization as a stage in the action potential of the heart can be seen in which of the following parts of the electrocardiogram?

Accepted Answer

A)  P wave 
B)  PR interval 
C)  QRS complex 
D)  T wave

Question 8

The ability of the heart to beat regularly is referred to as which of the following properties of cardiac tissue?

Accepted Answer

A)  Automaticity 
B)  Rhythmicity 
C)  Conductivity 
D)  Refractoriness

Question 9

The fundamental muscle unit responsible for myocardial contraction is the

Accepted Answer

A)  atrioventricular node. 
B)  sinoatrial node. 
C)  Purkinje fiber. 
D)  sarcomere.

Question 10

Epinephrine and norepinephrine exert which of the following effects on the heart?

Accepted Answer

A)  Decrease the heart rate 
B)  Increase force of myocardial contraction 
C)  Decrease conduction velocity 
D)  Lengthen the refractory period of the atrioventricular junction

Question 11

Myocardial tissue is nonresponsive to stimulation during which phase of the cardiac cycle?

Accepted Answer

A)  The final phase of diastole 
B)  The initial phase of systole 
C)  The final phase of systole 
D)  The initial phase of diastole

Question 12

The cardiac output is the product of which of the following two variables?

Accepted Answer

A)  Stroke volume and peripheral vascular resistance 
B)  Stroke volume and heart rate 
C)  Heart rate and blood pressure 
D)  Heart rate and peripheral vascular resistance

Question 13

The primary initiator of the conduction cycle in the heart is the

Accepted Answer

A)  Purkinje fibers. 
B)  atrioventricular node. 
C)  sinoatrial node. 
D)  bundle of His.

Question 14

Which of the following tissues of the heart are not affected by cardiac drugs?

Accepted Answer

A)  The myocardium 
B)  The pericardium 
C)  The conduction system 
D)  The coronary vessels

Question 15

Depolarization as a stage in the action potential of the heart can be seen in which of the following parts of the electrocardiogram?

Accepted Answer