Question 1

Which layer of the heart is responsible for the majority of its contractile force and contains branching muscle cells arranged in bundles?

Accepted Answer

Myocardium

Question 2

A patient presents with chest pain and is diagnosed with pericarditis. Which of the following is a primary function of the pericardium that is compromised in this condition?

Accepted Answer

Preventing overfilling of the heart with blood

Question 3

Blood returning from the systemic circulation enters the heart through which vessels?

Accepted Answer

Superior and inferior venae cavae

Question 4

Which of the following best describes the sequence of blood flow through the heart and lungs?

Accepted Answer

Right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary arteries → lungs → pulmonary veins → left atrium → bicuspid valve → left ventricle → aortic semilunar valve → aorta

Question 5

Which of the following statements about coronary circulation is correct?

Accepted Answer

Coronary arteries deliver blood to the heart muscle primarily when the heart is relaxed.

Question 6

A patient with mitral valve insufficiency is likely to experience which of the following?

Accepted Answer

Leakage of blood back into the left atrium during ventricular contraction

Question 7

Which of the following features is unique to cardiac muscle compared to skeletal muscle?

Accepted Answer

Intercalated discs containing desmosomes and gap junctions

Question 8

The plateau phase of the cardiac muscle action potential is primarily due to which ion movement?

Accepted Answer

Influx of Ca$$^{2+}$$ through slow channels

Question 9

Which property of autorhythmic cells allows the heart to beat without nervous system input?

Accepted Answer

Ability to spontaneously depolarize due to pacemaker potentials

Question 10

Which structure is considered the pacemaker of the heart and why?

Accepted Answer

SA node, because it has the highest autorhythmicity

Question 11

During the cardiac cycle, which event is responsible for the first heart sound (S1)?

Accepted Answer

Closure of AV valves

Question 12

Which formula correctly expresses cardiac output ($$CO) in $$terms of heart rate ($$HR) $$and stroke volume ($$SV$$)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 13

A marathon runner has a cardiac output ($$CO) of 17 L/$$min during peak exercise. If their heart rate ($$HR) is 170 $$beats/min, what is their stroke volume ($$SV$$)? Use the formula $$CO = HR 	imes SV.$$

Accepted Answer

$$SV = 100 mL/$$beat

Question 14

Which of the following would most likely cause tachycardia?

Accepted Answer

Increased sympathetic stimulation to the SA node

Question 15

According to the Frank-Starling Law of the Heart, an increase in end-diastolic volume ($$EDV) $$will have what effect on stroke volume ($$SV$$)?

Accepted Answer

Increase $$SV$$

Question 16

Which of the following best describes afterload and its effect on stroke volume ($$SV$$)?

Accepted Answer

Afterload is the pressure the ventricles must overcome to eject blood; increased afterload decreases $$SV$$

Question 17

A patient is given digoxin, a drug that increases contractility of the heart. Which of the following best describes the effect on stroke volume ($$SV$$)?

Accepted Answer

SV increases due to greater force of contraction

Question 18

Which of the following ECG intervals is most useful for diagnosing ventricular hypertrophy?

Accepted Answer

QRS complex

Question 19

During isovolumetric contraction, which of the following is true?

Accepted Answer

Both AV and semilunar valves are closed

Question 20

Which of the following would most likely result from chronic hypertension?

Accepted Answer

Increased afterload and decreased ability of ventricles to eject blood

Anatomy and Physiology of the Heart: Structure, Location, and Layers

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