Q: Calculate the cardiac output (CO) for a healthy adult with a heart rate (HR) of 75 beats/min and a stroke volume (SV) of 70 mL/beat. Use the formula $$CO = HR \times SV.$$

$$CO = 75 \times 70 = 5250\,\text{mL/min}$$

Question 1

Which structure in cardiac muscle is responsible for allowing rapid electrical communication between cells, enabling coordinated contraction?

Accepted Answer

Gap junctions

Question 2

During the plateau phase of the cardiac contractile cell action potential, which ions are primarily responsible for maintaining the membrane potential?

Accepted Answer

Ca++ and K+

Question 3

Which of the following best describes the function of the AV node in the cardiac conduction system?

Accepted Answer

Delays the impulse to allow atrial contraction

Question 4

A patient is given digitalis (digoxin). What effect does this medication have on cardiac contractility, and what is the underlying mechanism?

Accepted Answer

Increases contractility by raising intracellular Ca++ levels

Question 5

Calculate the cardiac output (CO) for a healthy adult with a heart rate (HR) of 75 beats/min and a stroke volume (SV) of 70 mL/beat. Use the formula $$CO = HR 	imes SV.$$

Accepted Answer

$$CO = 75 	imes 70 = 5250\,	ext{mL/min}$$

Question 6

Which phase of the cardiac contractile cell action potential is characterized by the rapid influx of Na+ ions?

Accepted Answer

Depolarization phase

Question 7

What is the effect of increased afterload on stroke volume (SV), and which equation describes this relationship?

Accepted Answer

Increased afterload decreases SV; $$SV = EDV - ESV$$

Question 8

Which of the following best describes the ejection fraction (EF) and its clinical significance?

Accepted Answer

EF is the percentage of blood pumped out of the ventricle in one beat

Question 9

A patient presents with dyspnea and orthopnea. Which condition is most likely responsible, and what is the underlying pathophysiology?

Accepted Answer

Left-sided heart failure; pulmonary congestion and edema

Question 10

During ventricular systole, which heart valves are closed and which are open?

Accepted Answer

AV valves closed; semilunar valves open

Question 11

Which division of the autonomic nervous system is the predominant influence over resting heart rate, and what is this effect called?

Accepted Answer

Parasympathetic; vagal tone

Question 12

Which of the following best describes the sequence of electrical excitation in the heart?

Accepted Answer

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

Question 13

Which event is represented by the QRS complex on an ECG?

Accepted Answer

Ventricular depolarization

Question 14

A patient’s ECG shows rapid, uncoordinated contractions of individual heart muscle fibers. What is the most likely diagnosis?

Accepted Answer

Ventricular fibrillation

Question 15

Which of the following conditions would most likely increase preload and thus increase stroke volume?

Accepted Answer

Exercise

Question 16

Which heart sound is produced by the closure of the atrioventricular (AV) valves during systole?

Accepted Answer

First heart sound (lub)

Question 17

Which of the following best describes the effect of sympathetic stimulation on the heart?

Accepted Answer

Increases heart rate and contractility

Question 18

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

Accepted Answer

$$SV = EDV - ESV$$

Question 19

A patient with poorly treated hypertension is at risk for which cardiac complication, and what is the mechanism?

Accepted Answer

Increased afterload; decreased stroke volume

Cardiac Contractility and Conduction: Study Notes for ANP College Students

Study Guide - Practice Questions

Study Guide - Flashcards