Question

Which of the following increases stroke volume?

decrease in preload

exercise

decrease in end diastolic volume (EDV)

severe blood loss

Answer 1

The answer is exercise. From the formula: stroke volume (SV) = EDV − end-systolic volume (ESV), we can clearly rule out option 3 (only if ESV decreases, SV will increase). From the Frank–Starling law of the heart, we can tell that preload and venous return are DIRECTLY proportional to SV, meaning, an decrease in preload (the degree to which the ventricles are stretched prior to contracting) DEcreases stroke volume, and severe blood loss also DEcreases venous return, and consequenty, DEcreases SV.