Q: A patient has a heart rate of 80 beats per minute and a stroke volume of 60 mL per beat. What is their cardiac output?

$$CO = 80 \times 60 = 4800\ \text{mL/min}$$

Question 1

Which of the following best describes the sequence of blood flow through the heart, starting from the vena cava?

Accepted Answer

Right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk → lungs → pulmonary veins → left atrium → bicuspid (mitral) valve → left ventricle → aortic semilunar valve → aorta

Question 2

During which phase of the cardiac cycle are the AV (atrioventricular) valves closed and the semilunar valves open?

Accepted Answer

Ventricular ejection

Question 3

Which event on an ECG corresponds to ventricular depolarization?

Accepted Answer

QRS complex

Question 4

What is the primary physiological significance of the plateau phase in the action potential of a cardiac contractile cell?

Accepted Answer

It prevents tetanus by prolonging the refractory period.

Question 5

Which of the following equations correctly represents cardiac output?

Accepted Answer

$$CO = HR 	imes SV$$

Question 6

A patient has a heart rate of 80 beats per minute and a stroke volume of 60 mL per beat. What is their cardiac output?

Accepted Answer

$$CO = 80 	imes 60 = 4800\ 	ext{mL/min}$$

Question 7

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

Accepted Answer

It must generate higher pressure to pump blood through the systemic circulation.

Question 8

Which of the following changes would most likely increase mean arterial pressure (MAP)?

Accepted Answer

An increase in total peripheral resistance (TPR)

Question 9

Which of the following statements about the baroreceptor reflex is correct?

Accepted Answer

It helps maintain blood pressure homeostasis by adjusting heart rate and vessel diameter.

Question 10

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

Accepted Answer

Increases heart rate and contractility

Question 11

During the cardiac cycle, what causes the 'lub' sound heard through a stethoscope?

Accepted Answer

Closure of the atrioventricular (AV) valves at the onset of ventricular systole

Question 12

Which of the following chemicals is most likely to cause vasodilation?

Accepted Answer

Histamine

Question 13

If the vagus nerve is stimulated, what is the expected effect on the heart?

Accepted Answer

Decreased heart rate due to increased parasympathetic activity

Question 14

Which of the following best explains why tetanus does not occur in cardiac muscle?

Accepted Answer

The long refractory period due to the plateau phase of the action potential

Question 15

Which of the following is the correct formula for mean arterial pressure (MAP)?

Accepted Answer

$$MAP = CO 	imes TPR$$

Question 16

A patient experiences a sudden drop in blood pressure. Which of the following responses would you expect from the baroreceptor reflex?

Accepted Answer

Increased sympathetic activity, leading to increased heart rate and vasoconstriction

Question 17

Which of the following best describes the role of the SA node in the heart?

Accepted Answer

It acts as the pacemaker, initiating action potentials that set the heart rate.

Question 18

Which of the following would most likely result from an increase in arteriolar radius?

Accepted Answer

Decreased resistance and increased blood flow

Question 19

Which of the following is a direct effect of norepinephrine on arterioles?

Accepted Answer

Vasoconstriction

Question 20

Which of the following best explains the effect of increased venous return on stroke volume?

Accepted Answer

It increases end-diastolic volume, which increases stroke volume via the Frank-Starling mechanism.

The Cardiovascular System: The Heart and Blood Vessels

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