Question 1

Which layer of the heart wall is responsible for the contractile force that pumps blood throughout the body?

Accepted Answer

Myocardium

Question 2

A patient suffers a myocardial infarction due to a blockage in a coronary artery. Which structure returns the deoxygenated blood from the heart tissue back to the right atrium?

Accepted Answer

Coronary sinus

Question 3

Which of the following best describes the function of the chordae tendineae and papillary muscles?

Accepted Answer

They prevent the backflow of blood by anchoring the AV valves during ventricular contraction.

Question 4

Trace the correct pathway of a red blood cell returning from the body to the lungs.

Accepted Answer

Right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk → lungs

Question 5

Which of the following is TRUE regarding the cardiac conduction system?

Accepted Answer

The SA node acts as the pacemaker of the heart.

Question 6

During which phase of the cardiac cycle are all four heart valves closed and the ventricles are relaxing?

Accepted Answer

Isovolumetric relaxation

Question 7

Calculate the cardiac output (CO) if the heart rate (HR) is 80 beats/min and the stroke volume (SV) is 70 mL/beat. Use the formula $$CO = HR 	imes SV.$$

Accepted Answer

$$CO = 5600\ 	ext{mL/min}$$

Question 8

Which event is responsible for the 'lubb' sound heard during auscultation of the heart?

Accepted Answer

Closing of the AV valves

Question 9

A patient has an end-diastolic volume (EDV) of 120 mL and an end-systolic volume (ESV) of 50 mL. What is the stroke volume (SV)? Use the formula $$SV = EDV - ESV.$$

Accepted Answer

$$SV = 70\ 	ext{mL}$$

Question 10

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

Accepted Answer

Increased preload leads to increased force of contraction and stroke volume.

Question 11

Which of the following is a distinguishing feature of cardiac muscle tissue compared to skeletal muscle?

Accepted Answer

Cardiac muscle cells are connected by intercalated discs containing gap junctions and desmosomes.

Question 12

Which of the following would most likely cause a decrease in cardiac output?

Accepted Answer

Decreased heart rate and decreased stroke volume

Question 13

Which of the following best describes the function of the semilunar valves?

Accepted Answer

They prevent backflow of blood into the ventricles after ventricular contraction.

Question 14

A patient presents with ventricular fibrillation. Which of the following best describes what you would expect to see on their ECG?

Accepted Answer

No recognizable waves or complexes

Question 15

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

Accepted Answer

Decreased heart rate

Question 16

Which of the following best describes the role of the pericardial fluid?

Accepted Answer

It reduces friction between the heart and surrounding structures during contraction.

Question 17

Which of the following would most likely increase the risk of myocardial infarction?

Accepted Answer

Obstruction of a coronary artery due to atherosclerosis

Question 18

Which of the following best explains why the left ventricle has a thicker wall than the right ventricle?

Accepted Answer

It pumps blood to the entire systemic circulation.

Question 19

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

Accepted Answer

SA node → AV node → AV bundle → Purkinje fibers

Question 20

Which of the following best describes the effect of a positive inotropic agent on the heart?

Accepted Answer

It increases the force of contraction.

The Cardiovascular System I: The Heart – Structure, Function, and Physiology

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