Q: Calculate the stroke volume (SV) if the end-diastolic volume (EDV) is $$120\, \text{ml}$$ and the end-systolic volume (ESV) is $$50\, \text{ml}.$$

$$SV = EDV - ESV = 70\, \text{ml}$$

Question 1

Which of the following best describes the primary mechanism by which blood flows through the heart during the cardiac cycle?

Accepted Answer

Blood flows in response to pressure gradients created by contraction and relaxation of cardiac chambers.

Question 2

During ventricular contraction, what causes the atrioventricular (AV) valves to close?

Accepted Answer

Blood pushes against the AV valves from the ventricles as ventricular pressure rises above atrial pressure.

Question 3

Which heart sound is typically longer and louder, and what event causes it?

Accepted Answer

S1, caused by closure of AV valves.

Question 4

A heart murmur is most commonly associated with which of the following?

Accepted Answer

Defective valves causing turbulent blood flow.

Question 5

Which phase of the cardiac cycle is characterized by the ventricles being filled with blood while both sets of valves are closed and no change in ventricular volume occurs?

Accepted Answer

Isovolumetric contraction phase

Question 6

What is the approximate end-diastolic volume (EDV) in each ventricle at the end of atrial systole?

Accepted Answer

$$\approx 120\, 	ext{ml}$$

Question 7

During the ventricular ejection phase, what causes the semilunar valves to open?

Accepted Answer

Pressure in the ventricles rises above that in the pulmonary trunk and aorta.

Question 8

Calculate the stroke volume (SV) if the end-diastolic volume (EDV) is $$120\, 	ext{ml}$$ and the end-systolic volume (ESV) is $$50\, 	ext{ml}.$$

Accepted Answer

$$SV = EDV - ESV = 70\, 	ext{ml}$$

Question 9

Which of the following best explains why S3 and S4 heart sounds may be heard in a healthy heart?

Accepted Answer

They can result from normal recoil and filling dynamics of the ventricular walls.

Question 10

During which phase of the cardiac cycle does the pressure in the ventricles fall below that in the atria, allowing AV valves to open and blood to flow into the ventricles?

Accepted Answer

Ventricular filling phase

Question 11

Which of the following statements about the cardiac cycle is correct?

Accepted Answer

Atrial and ventricular diastoles and systoles occur at different times due to AV node delay.

Question 12

What is the main function of heart valves during the cardiac cycle?

Accepted Answer

To prevent backflow of blood and ensure unidirectional flow.

Question 13

A patient presents with a heart murmur. Which of the following is the most likely underlying cause?

Accepted Answer

Defective chordae tendineae or holes in the septum.

Question 14

Which equation correctly represents the relationship between cardiac output (CO), heart rate (HR), and stroke volume (SV)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 15

During isovolumetric relaxation, which of the following events occurs?

Accepted Answer

Semilunar valves snap shut, S2 heart sound is heard, and AV valves remain closed.

Question 16

Which of the following best describes the Wiggers diagram?

Accepted Answer

It provides a comprehensive overview of electrical and mechanical events in the left side of the heart during each phase of the cardiac cycle.

Question 17

If a patient’s end-diastolic volume (EDV) is $$130\, 	ext{ml}$$ and their end-systolic volume (ESV) is $$60\, 	ext{ml}$$, what is their stroke volume (SV)?

Accepted Answer

$$SV = 70\, 	ext{ml}$$

Question 18

Which of the following is true regarding the pressure changes in the left and right ventricles during the cardiac cycle?

Accepted Answer

Maximum pressure in the left ventricle is higher than in the right ventricle.

Question 19

Which event marks the beginning of ventricular systole?

Accepted Answer

Isovolumetric contraction, where pressure rises but volume does not change.

Mechanical Physiology of the Heart: The Cardiac Cycle

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