Which Factor Directly Influences Preload

Question

Which factor directly influences preload?
A) contractility
B) heart rate
C) stroke volume
D) venous return
E) parasympathetic tone

Accepted Answer

Preload is the amount of blood that returns to the heart and stretches the ventricles before they contract. Venous return is the major factor that directly influences preload. An increase in venous return will increase preload, and a decrease in venous return will decrease preload. Factors such as contractility, heart rate, stroke volume, and parasympathetic tone can indirectly affect preload through their impact on venous return.