Deck 24: Overview of the Cardiovascular System

Question 1

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

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

Answer 1

Calcium

Question 2

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

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

Answer 2

Increased stroke volume

Question 3

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

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

Answer 3

It slows the heart rate

Question 4

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

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 5

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

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

Question 6

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

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

Question 7

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

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 8

Vagal stimulation of the heart leads to

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

Question 9

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

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 10

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

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

Question 11

The fundamental muscle unit responsible for myocardial contraction is the

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

Question 12

The effective refractory period is when the heart cell

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 13

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

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

Question 14

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

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

Question 15

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

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