Question

An increase in venous return will _______.

increase EDV only
increase the contractility of the heart
increase EDV and therefore, increase stroke volume
increase stroke volume only

Answer 1

The correct answer is: increase EDV and therefore, increase stroke volume.

Step-by-step explanation:

Stroke volume refers to the volume of blood that is pumped from the left ventricle in every beat. Stroke volume, along with heart rate, determines the cardiac output and is used to calculate ejection fraction. An abnormal stroke volume correlates to heart malfunction.

Stroke volume (SV) is calculated by subtracting end-systolic volume (ESV) from end-diastolic volume (EDV).

SV = EDV - ESV

For this reason, one can infer that an increase in EDV will produce an increase in stroke volume; and a decrease in EDV will produce a decrease in stroke volume.

An increase in venous return will produce an increase in EDV and stroke volume because it stretches the muscle fibers thereby increasing their preload.

Answer 2

Increase EDV and therefore, increase stroke volume.

Step-by-step explanation:

EDV is the volume of blood which filled the ventricle before its contraction while ESV is the volume of blood remain in ventricle after ejection.

When venous return increases, this will increase the pressure on ventricle contraction which can lead to eject of addition blood returned to it.

So, increase in EDV results in an increase of stroke volume (SV).