$\mathrm{CO} = \mathrm{HR} \times \mathrm{SV}$

Question 1

Which structure in the heart is primarily responsible for setting the pace of the heartbeat under normal conditions?

Accepted Answer

Sinoatrial (SA) node

Question 2

If the SA node fails to function, which structure can act as a secondary pacemaker, and what is its typical rate?

Accepted Answer

AV node at 50 bpm

Question 3

During the cardiac cycle, which event immediately follows the depolarization of the atria?

Accepted Answer

Atrial contraction

Question 4

Which of the following best describes the function of the AV node delay?

Accepted Answer

It ensures the atria have time to contract and fill the ventricles before ventricular contraction.

Question 5

What is the correct formula for calculating stroke volume?

Accepted Answer

$\mathrm{Stroke\ Volume} = \mathrm{EDV} - \mathrm{ESV}$

Question 6

A patient has an end-diastolic volume (EDV) of 120 mL and an end-systolic volume (ESV) of 50 mL. What is their stroke volume?

Accepted Answer

70 mL

Question 7

Which of the following mechanisms does NOT increase venous return to the heart?

Accepted Answer

Parasympathetic stimulation of veins

Question 8

According to the Frank-Starling law, what happens to stroke volume as end-diastolic volume (EDV) increases?

Accepted Answer

Stroke volume increases

Question 9

Which chemical has a positive inotropic effect on the heart?

Accepted Answer

Epinephrine

Question 10

What is the correct formula for cardiac output?

Accepted Answer

$\mathrm{CO} = \mathrm{HR} 	imes \mathrm{SV}$

Question 11

A patient has a heart rate of 80 bpm and a stroke volume of 60 mL. What is their cardiac output?

Accepted Answer

4.8 L/min

Question 12

Which event is responsible for the first heart sound ('lub') heard during auscultation?

Accepted Answer

Closure of AV valves

Question 13

Which phase of the cardiac cycle is characterized by all valves being shut and no change in ventricular blood volume?

Accepted Answer

Isovolumic ventricular relaxation

Question 14

What effect does parasympathetic stimulation have on the autorhythmic cells of the heart?

Accepted Answer

It hyperpolarizes the membrane and slows depolarization, decreasing heart rate.

Question 15

Which of the following best describes the direction of ventricular contraction in the heart?

Accepted Answer

From apex to base

Question 16

A patient’s ECG shows an abnormal QRS complex. Which cardiac event is most likely affected?

Accepted Answer

Ventricular depolarization

Question 17

Which of the following is the correct formula for ejection fraction?

Accepted Answer

$\mathrm{Ejection\ Fraction} = \dfrac{\mathrm{Stroke\ Volume}}{\mathrm{EDV}}$

Question 18

If a patient has a stroke volume of 65 mL and an EDV of 125 mL, what is their ejection fraction?

Accepted Answer

52%

Question 19

Which of the following would most likely decrease cardiac contractility?

Accepted Answer

A negative inotropic agent

Question 20

During ventricular diastole, which event occurs?

Accepted Answer

Ventricular pressure drops below atrial pressure and AV valves open

Ch 14b Cardiovascular Physiology: Electrical Conduction and Cardiac Action Potential

Study Guide - Practice Questions