Which of the following correctly describes the diastolic filling of the left ventricle?

The correct choice is that diastolic filling of the left ventricle is a passive process. During diastole, the heart muscle relaxes, allowing the left ventricle to fill with blood coming from the left atrium. This filling phase primarily relies on the pressure gradient between the left atrium and the left ventricle. When the left atrium is at a higher pressure than the left ventricle during this phase, blood flows passively through the open mitral valve into the ventricle.

Although atrial contraction contributes to ventricular filling, particularly in the late stages, the majority of filling occurs passively as the ventricle relaxes and expands. The description that it involves both passive filling primarily and some active filling during atrial contraction highlights the importance of pressure differences before any contraction of the atria occurs.

The other options do not accurately describe the process: Diastolic filling does not happen solely during atrial contraction, nor does it exclude the involvement of atrioventricular valves, as the mitral valve plays a crucial role in allowing blood to enter the ventricle. Additionally, diastolic filling results in an increase in left ventricular volume as blood enters, rather than a decrease. Thus