Which factors are determinants of stroke volume?

The correct answer focuses on several physiological factors that directly influence stroke volume, which is the amount of blood the heart ejects with each beat.

When considering gender, it is important to recognize that anatomical and physiological differences can impact heart size and structure, which in turn affect stroke volume. Men typically have larger hearts compared to women, resulting in a greater stroke volume due to a higher volume capacity.

Heart size is crucial because a larger heart can typically accommodate more blood in the ventricles, allowing for a greater ejection during contraction. The contractility of the heart refers to the strength of the heart's contractions; increased contractility improves the heart's ability to pump blood efficiently, thereby increasing stroke volume.

The duration of contraction also plays a role, as longer contractions can lead to more blood being pushed out, whereas shorter contractions may not allow the chambers enough time to fill completely. Overall, these factors interrelate in a way that has a significant effect on how effectively the heart can pump blood, making them critical determinants of stroke volume.

In contrast, the other options provided do not encompass the primary physiological aspects of stroke volume, focusing instead on unrelated factors.