Q: Using the diagram, calculate the stroke volume (SV) if the end-diastolic volume (EDV) is 135 mL and the end-systolic volume (ESV) is 65 mL. Use the formula $$SV = EDV - ESV.$$

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

Question 1

Refer to the pressure-volume loop shown. What event is occurring at point B on the curve, where left ventricular pressure rises sharply but volume remains constant?

Accepted Answer

Isovolumetric contraction

Question 2

At which point on the pressure-volume loop does the mitral (bicuspid) valve open, and what is the physiological significance of this event?

Accepted Answer

Point A; this marks the beginning of ventricular filling

Question 3

Using the diagram, calculate the stroke volume (SV) if the end-diastolic volume (EDV) is 135 mL and the end-systolic volume (ESV) is 65 mL. Use the formula $$SV = EDV - ESV.$$

Accepted Answer

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

Question 4

Which phase of the cardiac cycle is represented by the segment from point C to point D on the pressure-volume loop, and what is happening to the ventricular volume?

Accepted Answer

Isovolumetric relaxation; volume remains constant

Question 5

If afterload increases (e.g., due to hypertension), how would the pressure-volume loop change?

Accepted Answer

The loop would become taller and narrower, indicating increased pressure and decreased stroke volume

Question 6

What does the width of the pressure-volume loop represent, and how is it calculated?

Accepted Answer

It represents the stroke volume, calculated as $$SV = EDV - ESV$$

Question 7

During which phase of the pressure-volume loop does the aortic (semilunar) valve open, and what is the consequence for ventricular pressure and volume?

Accepted Answer

At point B; ventricular pressure exceeds aortic pressure, and volume begins to decrease as blood is ejected

Question 8

If a patient has a decreased contractility due to heart failure, how would this affect the pressure-volume loop?

Accepted Answer

The loop would become narrower, indicating decreased stroke volume and increased ESV

Question 9

Which of the following best describes the physiological event occurring at point D on the pressure-volume loop?

Accepted Answer

The mitral valve closes, marking the end of ventricular filling

Question 10

If the end-diastolic volume (EDV) increases while end-systolic volume (ESV) remains constant, what happens to stroke volume and the area of the pressure-volume loop?

Accepted Answer

Stroke volume increases and the loop area increases

Question 11

Which of the following best explains why the left ventricle must generate higher pressures than the right ventricle during the cardiac cycle?

Accepted Answer

The left ventricle pumps blood to the systemic circuit, which has higher resistance

Question 12

If a patient’s pressure-volume loop shows a much higher ESV, what might this indicate about their cardiac function?

Accepted Answer

Decreased contractility or increased afterload

Question 13

Which of the following would cause the pressure-volume loop to shift to the right, indicating an increased EDV?

Accepted Answer

Increased preload

Question 14

What is the clinical significance of the area inside the pressure-volume loop?

Accepted Answer

It represents the work done by the left ventricle during one cardiac cycle

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