Final answer:
The aorta acts as a pressure reservoir, causing blood to move through the vasculature throughout the entire cardiac cycle.
Step-by-step explanation:
The aorta acts as a pressure reservoir, causing blood to move through the vasculature throughout the entire cardiac cycle.
Recall that blood moves from higher pressure to lower pressure. It is pumped from the heart into the arteries at high pressure. In the venous system, increased pressure in the veins does not decrease flow as it does in arteries, but actually increases flow. Since pressure in the veins is normally relatively low, for blood to flow back into the heart, the pressure in the atria during atrial diastole must be even lower. It normally approaches zero, except when the atria contract.