Q: A person at rest has an end-diastolic volume ($$EDV) of 135 mL $$and an end-systolic volume ($$ESV) of 65 mL. $$What is their stroke volume ($$SV$$)?

$$SV = 135 \text{ mL} - 65 \text{ mL} = 70 \text{ mL}$$

Question 1

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

Accepted Answer

Because it pumps blood to the entire systemic circuit, requiring greater force to overcome higher resistance.

Question 2

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

Accepted Answer

Late diastole

Question 3

Which of the following statements about veins is TRUE?

Accepted Answer

Veins carry blood toward the heart, regardless of oxygenation status.

Question 4

A patient has a mutation that prevents the inactivation of voltage-gated sodium channels in cardiac myocytes. Which phase of the cardiac action potential would be most directly affected?

Accepted Answer

The rapid depolarization phase (phase 0)

Question 5

Which of the following best describes the function of intercalated discs in cardiac muscle?

Accepted Answer

They provide electrical and mechanical connection between cardiac cells, allowing coordinated contraction.

Question 6

If the semilunar valves failed to close properly, which of the following would most likely occur?

Accepted Answer

Blood would flow backward from the arteries into the ventricles during ventricular relaxation.

Question 7

Which equation correctly calculates stroke volume ($$SV) $$based on end-diastolic volume ($$EDV) $$and end-systolic volume ($$ESV$$)?

Accepted Answer

$$SV = EDV - ESV$$

Question 8

A person at rest has an end-diastolic volume ($$EDV) of 135 mL $$and an end-systolic volume ($$ESV) of 65 mL. $$What is their stroke volume ($$SV$$)?

Accepted Answer

$$SV = 135 	ext{ mL} - 65 	ext{ mL} = 70 	ext{ mL}$$

Question 9

Which event is responsible for the first heart sound ('lub') heard during the cardiac cycle?

Accepted Answer

Closure of the atrioventricular (AV) valves during isovolumic contraction

Question 10

Why is the action potential in cardiac myocytes characterized by a plateau phase?

Accepted Answer

To ensure the refractory period lasts as long as the contraction, preventing summation and tetanus

Question 11

Which of the following best describes the direction of blood flow through the heart and major vessels?

Accepted Answer

Right atrium → right ventricle → pulmonary artery → lungs → left atrium → left ventricle → aorta

Question 12

A patient is found to have a blockage in the coronary arteries. Which of the following is the most direct consequence?

Accepted Answer

Reduced oxygen delivery to the cardiac muscle cells

Question 13

Which of the following is NOT a primary function of the circulatory system?

Accepted Answer

Synthesis of hormones

Question 14

Which of the following statements about the pulmonary circuit is correct?

Accepted Answer

It carries deoxygenated blood from the right ventricle to the lungs and returns oxygenated blood to the left atrium.

Question 15

Which of the following best explains why large multicellular organisms require a circulatory system?

Accepted Answer

To actively transport gases, nutrients, and wastes over distances too great for diffusion alone

Question 16

Which of the following is TRUE regarding the color of human blood?

Accepted Answer

Blood is always red due to the presence of hemoglobin, regardless of oxygenation.

Question 17

Which of the following animals has blue blood due to the presence of hemocyanin?

Accepted Answer

Horseshoe crab

Question 18

Which of the following best describes the relationship between pressure and volume in the heart during ventricular contraction?

Accepted Answer

As volume decreases, pressure increases.

Question 19

Which of the following is the correct sequence of events during the cardiac cycle?

Accepted Answer

Late diastole → atrial systole → isovolumic contraction → ventricular systole → isovolumic relaxation

Question 20

Which of the following best explains why cardiac muscle cannot undergo tetanus (sustained contraction)?

Accepted Answer

Because the plateau phase of the action potential ensures the refractory period lasts as long as the contraction.

The Cardiovascular System: Structure, Function, and Cardiac Muscle Physiology

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