What does stroke volume depend on?

Stroke volume is defined as the volume of blood pumped from the left ventricle of the heart with each contraction. It is influenced primarily by two main factors: end diastolic volume (EDV) and end systolic volume (ESV).

End diastolic volume refers to the amount of blood in the ventricle at the end of filling (diastole), just before contraction. A higher EDV typically leads to a larger stroke volume due to the Frank-Starling mechanism, which states that the more the cardiac muscle fibers are stretched (up to a physiological limit), the more forcefully they will contract. Therefore, increased venous return leads to an increase in EDV and, consequently, stroke volume.

End systolic volume, on the other hand, is the volume of blood remaining in the ventricle after contraction (systole). A lower ESV will increase stroke volume because less blood is retained in the ventricle, allowing more blood to be pumped out with each heartbeat.

Thus, stroke volume can be mathematically expressed as:

Stroke Volume = End Diastolic Volume - End Systolic Volume

This relationship emphasizes that both EDV and ESV are essential in determining stroke volume. When looking