Question 1

Which of the following best describes the function of the sinoatrial (SA) node in the heart's intrinsic conduction system?

Accepted Answer

It acts as the pacemaker, initiating impulses that set the heart's rhythm.

Question 2

During the action potential of a cardiac pacemaker cell, which ion's influx is primarily responsible for the depolarization phase?

Accepted Answer

Ca2+

Question 3

A patient presents with a heart rate of 45 beats per minute and an ECG showing absent P waves. Which structure is most likely pacing the heart?

Accepted Answer

Atrioventricular (AV) node

Question 4

Which of the following equations correctly represents cardiac output (CO)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 5

A patient with persistent high blood pressure is at risk for which of the following changes in the heart due to increased afterload?

Accepted Answer

Increased end systolic volume (ESV)

Question 6

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

Accepted Answer

Isovolumetric contraction

Question 7

Which of the following best explains the benefit of the plateau phase in the action potential of contractile cardiac muscle cells?

Accepted Answer

It ensures a long refractory period, preventing tetanic contractions.

Question 8

A patient is diagnosed with ventricular fibrillation. What is the most immediate risk associated with this condition?

Accepted Answer

Cessation of effective circulation, risking brain death

Question 9

Which of the following would most likely increase stroke volume (SV)?

Accepted Answer

Increased preload

Question 10

Which heart sound is associated with the closing of the semilunar (SL) valves?

Accepted Answer

Second heart sound (dup)

Question 11

A 25-year-old athlete has a resting heart rate of 55 beats per minute. Which term best describes this condition?

Accepted Answer

Bradycardia

Question 12

Which of the following is the correct sequence of excitation through the intrinsic conduction system of the heart?

Accepted Answer

SA node → AV node → AV bundle → bundle branches → Purkinje fibers

Question 13

Which of the following would most likely be seen on an ECG if the AV node fails to conduct some SA node impulses?

Accepted Answer

More P waves than QRS complexes

Question 14

Which of the following best describes the Frank-Starling law of the heart?

Accepted Answer

The greater the preload (stretch), the greater the force of contraction.

Question 15

Which of the following would be a likely effect of administering a drug that blocks β1-adrenergic receptors in the heart?

Accepted Answer

Decreased heart rate and contractility

Question 16

A patient with congestive heart failure (CHF) due to left-sided failure is most likely to experience which of the following?

Accepted Answer

Pulmonary congestion

Question 17

Which of the following best explains why the heart cannot undergo tetanic contractions?

Accepted Answer

The long refractory period due to the plateau phase prevents tetanus.

Question 18

Which of the following is the correct formula for stroke volume (SV)?

Accepted Answer

$$SV = EDV - ESV$$

Question 19

Which fetal heart structure allows blood to bypass the pulmonary circulation by connecting the right and left atria?

Accepted Answer

Foramen ovale

Question 20

A patient is given a calcium channel blocker. Which of the following effects would you expect on the heart?

Accepted Answer

Decreased contractility

ch 18 Electrical and Mechanical Events of the Heart: Cardiac Physiology and Regulation pt 2

Study Guide - Practice Questions