Question

During which of the conditions (sitting, reclining, standing, or after exercise) is peripheral resistance the lowest? What are the physiological mechanisms, which lower the peripheral resistance during the condition given as your answer?

Answer 1

Peripheral resistance is at its lowest after exercise, mainly due to vasodilation and increased blood flow, facilitated by the skeletal muscle pump which aids venous return and decreases resistance.

Step-by-step explanation:

Peripheral resistance is the lowest after exercise due to the physiological mechanisms of vasodilation and increased blood flow. During exercise, the body's demand for oxygen increases, leading to vasodilation of arterioles and capillaries, which decreases resistance. Additionally, the skeletal muscle pump enhances venous return, further reducing peripheral resistance.

Exercise prompts vessels to widen, or vasodilate, to allow greater blood flow to meet the metabolic demands of tissues. This vasodilation leads to a decrease in resistance within the peripheral circulatory system. Another contributing factor is the skeletal muscle pump, which works by compressing veins during muscle contraction, effectively pushing blood back towards the heart and lowering resistance in the extremities. During post-exercise recovery, while the increase in blood flow persists, the active muscle pumps and respiratory movements also support venous return, maintaining a low peripheral resistance state.