Stroke volume is equal to end diastolic volume minus end systolic volume. Which expression represents this relationship?

Stroke volume is equal to end diastolic volume minus end systolic volume. Which expression represents this relationship?

• A. End Diastolic Volume - End Systolic Volume
• B. End Systolic Volume - End Diastolic Volume
• C. Preload - Afterload
• D. Afterload - Preload

Answer: (A)

Stroke volume is the amount of blood ejected by the ventricle each heartbeat. It comes from how much the ventricle fills to at the end of diastole (end diastolic volume) minus how much remains after contraction (end systolic volume). So the direct expression is End Diastolic Volume minus End Systolic Volume. Swapping the order would give a negative value, which isn’t meaningful for stroke volume. Preload and afterload describe filling and the pressure against which the ventricle ejects, but they aren’t the arithmetic expression for stroke volume.

Stroke volume is the amount of blood ejected by the ventricle each heartbeat. It comes from how much the ventricle fills to at the end of diastole (end diastolic volume) minus how much remains after contraction (end systolic volume). So the direct expression is End Diastolic Volume minus End Systolic Volume. Swapping the order would give a negative value, which isn’t meaningful for stroke volume. Preload and afterload describe filling and the pressure against which the ventricle ejects, but they aren’t the arithmetic expression for stroke volume.