Question

Increasing ________ would increase the sarcomere length in contractile cardiomyocytes leading to increased _________.

a. end diastolic volume, stroke volume

b. end systolic volume, stroke volume

c. end diastolic volume, heart rate

d. end diastolic volume, pressure that opens the aortic valve

e. end systolic volume, stroke volume

Answer 1

Increasing END DIASTOLIC VOLUME would increase the sarcomere length in contractile cardiomyocytes leading to increased STROKE VOLUME

A greater volume of blood returning to the heart during diastole equates to greater pressures generated initially by the heart's contractile elements. In a clinical situation, when increased quantities of blood flow into the heart (increasing preload), the walls of the heart stretch. The cardiac muscle then contracts with increased force and, within limits, empties the expanded chambers with increasing stroke volume. There is an optimal sarcomere length and thus an optimal fiber length from which the most forceful contraction occurs. The left ventricle normally operates at an LV end-diastolic volume with less than optimal fiber lengths. The clinical implication of this is that stroke volume increases with increasing preload until the optimal fiber length of the myocardium is reached.

end-diastolic volume (EDV) is the volume of blood in the right and/or left ventricle at end load or filling in (diastole) or the amount of blood in the ventricles just before systole.

preload is the amount of sarcomere stretch experienced by cardiac muscle cells, called cardiomyocytes, at the end of ventricular filling during diastole

Stroke Volume (SV) is the volume of blood in millilitres ejected from the each ventricle due to the contraction of the heart muscle which compresses these ventricles.