How does enhanced preload affect stroke volume?

Enhanced preload refers to the increased volume of blood filling the heart's ventricles before contraction, which is a crucial aspect of the cardiac cycle. This increase in preload is primarily influenced by the volume of blood returning to the heart via the veins. When preload is enhanced, the ventricles stretch more due to the increased volume; according to the Frank-Starling law of the heart, this leads to a more forceful contraction.

The law of the heart states that, up to a certain point, the more the cardiac muscle fibers are stretched (because of the increased volume), the stronger the contraction will be. This increased force of contraction results in a greater volume of blood being ejected from the heart with each heartbeat, thereby enhancing stroke volume.

In summary, enhanced preload increases the amount of blood returned to the heart and allows for stronger contractions, which leads to an increase in stroke volume, making the correct choice the option that states it enhances stroke volume.