Which statement best describes stroke volume?

• A. It is the amount of blood pumped per minute.
• B. It is the volume of blood remaining in the ventricle after contraction.
• C. It is the volume of blood ejected per beat during diastole.
• D. It is the amount of blood pumped out of the ventricle during each contraction.

Answer: (D)

Stroke volume is the amount of blood ejected from a ventricle with each heartbeat. It differs from cardiac output, which is the total blood pumped per minute and equals stroke volume multiplied by heart rate. The other descriptions don’t fit: the total amount pumped per minute is cardiac output, not per beat; the volume remaining in the ventricle after contraction is the end-systolic volume; and ejection happens during systole, not diastole. So the correct description is the amount of blood pumped out of the ventricle during each contraction.