Questions: What is the stroke volume if the end diastolic volume (EDV) is 120 mL / beat and the end systolic volume is 50 mL / beat. (A) 170 mL / beat (B) 50 mL / beat (C) 70 mL / beat (D) 120 mL / beat

The answer is (C): \(70 \, \text{mL/beat}\).

To determine the stroke volume, we use the formula:

\[ \text{Stroke Volume (SV)} = \text{End Diastolic Volume (EDV)} - \text{End Systolic Volume (ESV)} \]

Given:

• End Diastolic Volume (EDV) = \(120 \, \text{mL/beat}\)
• End Systolic Volume (ESV) = \(50 \, \text{mL/beat}\)

Substitute these values into the formula:

\[ \text{SV} = 120 \, \text{mL/beat} - 50 \, \text{mL/beat} = 70 \, \text{mL/beat} \]

Explanation for each option:

• (A) \(170 \, \text{mL/beat}\): Incorrect. This value is obtained by adding EDV and ESV, which is not the correct method for calculating stroke volume.
• (B) \(50 \, \text{mL/beat}\): Incorrect. This value is the ESV, not the stroke volume.
• (C) \(70 \, \text{mL/beat}\): Correct. This is the result of subtracting ESV from EDV.
• (D) \(120 \, \text{mL/beat}\): Incorrect. This value is the EDV, not the stroke volume.

In summary, the stroke volume is \(70 \, \text{mL/beat}\).