Q: Calculate the cardiac output if the heart rate is 80 beats per minute and the stroke volume is 75 mL per beat. Use the formula $$CO = HR \times SV.$$

$$CO = 80 \times 75 = 6000\ \text{mL/min}$$

Q: A patient has an end diastolic volume (EDV) of 130 mL and an end systolic volume (ESV) of 60 mL. What is the stroke volume (SV)? Use the formula $$SV = EDV - ESV.$$

$$SV = 130 - 60 = 70\ \text{mL}$$

Question 1

Which of the following best describes the function of the coronary circulation?

Accepted Answer

To supply the myocardium with oxygenated blood

Question 2

A patient presents with chest pain due to ischemia in the heart muscle. What is the most likely diagnosis?

Accepted Answer

Angina pectoris

Question 3

Which structure is responsible for initiating the action potential that sets the heart rate?

Accepted Answer

Sinoatrial (SA) node

Question 4

Which of the following is a key characteristic of cardiomyocytes that prevents tetanus in the heart?

Accepted Answer

A long refractory period

Question 5

During the plateau phase of the contractile cardiac cell action potential, which ion is primarily responsible for maintaining depolarization?

Accepted Answer

$$Ca^{2+}$$

Question 6

Calculate the cardiac output if the heart rate is 80 beats per minute and the stroke volume is 75 mL per beat. Use the formula $$CO = HR 	imes SV.$$

Accepted Answer

$$CO = 80 	imes 75 = 6000\ 	ext{mL/min}$$

Question 7

Which of the following ECG findings is most consistent with third-degree (complete) AV block?

Accepted Answer

P waves and QRS complexes occur independently of each other

Question 8

A patient has an end diastolic volume (EDV) of 130 mL and an end systolic volume (ESV) of 60 mL. What is the stroke volume (SV)? Use the formula $$SV = EDV - ESV.$$

Accepted Answer

$$SV = 130 - 60 = 70\ 	ext{mL}$$

Question 9

Which of the following would most likely increase preload in the heart?

Accepted Answer

Increased venous return

Question 10

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

Accepted Answer

Increases heart rate and contractility

Question 11

A patient with a history of myocardial infarction is found to have an ejection fraction (EF) of 40%. Which formula is used to calculate EF, and what does this value indicate?

Accepted Answer

$$EF = \frac{SV}{EDV}$$; this value is abnormally low and may indicate heart failure

Question 12

Which of the following arrhythmias is characterized by multiple ectopic foci in the atria, resulting in an irregularly irregular rhythm and absence of distinct P waves on ECG?

Accepted Answer

Atrial fibrillation

Question 13

Which of the following best explains why cardiac muscle cannot undergo tetanus?

Accepted Answer

The refractory period in cardiac muscle is nearly as long as the contraction itself

Question 14

Which of the following would most likely decrease stroke volume?

Accepted Answer

Increased afterload

Question 15

Which of the following is a direct effect of increased parasympathetic (vagal) stimulation on the heart?

Accepted Answer

Decreased heart rate

Question 16

A patient is diagnosed with congestive heart failure (CHF). Which of the following is NOT a common cause of CHF?

Accepted Answer

Increased aerobic exercise

Question 17

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

Accepted Answer

The greater the stretch of cardiac muscle fibers, the stronger the contraction, up to an optimal point

Question 18

Which of the following is the correct sequence of electrical conduction through the heart?

Accepted Answer

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

Question 19

Which of the following best describes the effect of increased venous return on cardiac output, assuming all other factors remain constant?

Accepted Answer

Increased venous return increases preload, which increases stroke volume and thus cardiac output

The Heart: Structure, Function, and Cardiac Physiology

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