TRUE or False: atrial systole is responsible for "most" of venous return.
wouldn't this be false? I was thinking it should say ventricular systole instead, but I'm not sure. Help?
False. See Phase 5.
http://en.wikipedia.org/wiki/Cardiac_cycle
You are correct, the statement is false. Atrial systole is not responsible for "most" of venous return. Venous return refers to the flow of blood back to the heart from the systemic circulation. While atrial systole does contribute to venous return to some extent, it is not the primary mechanism.
The majority of venous return is actually driven by the pumping action of the heart during ventricular systole. Ventricular systole refers to the contraction of the ventricles, specifically the left ventricle, which pumps blood out of the heart into the systemic circulation. This creates a pressure gradient that helps to push blood forward and facilitate the flow of blood back to the heart through the veins.
Additionally, other factors such as skeletal muscle contraction, the presence of valves in the veins, and changes in intrathoracic pressure during respiration also play a role in promoting venous return.
Therefore, the correct statement would be that ventricular systole is responsible for "most" of venous return, not atrial systole.