During exercise, what effect does adrenaline have on blood flow?

During exercise, what effect does adrenaline have on blood flow?

• A. Dilates arteries to muscles
• B. Constricts arteries to muscle
• C. Reduces blood flow to the brain
• D. Increases venous return from the heart

Answer: (A)

Adrenaline helps ensure working muscles get more blood by causing vasodilation in the arteries supplying them. It binds to beta-2 receptors on the smooth muscle of skeletal muscle arterioles, relaxing those vessels and lowering resistance. That increased diameter lets more blood flow to the muscles as they demand more oxygen and nutrients during exercise. At the same time, adrenaline shunts blood away from less-essential areas like the gut and skin by constricting their vessels, further prioritizing muscle perfusion. It also raises heart rate and the strength of each beat, boosting overall cardiac output to deliver the increased blood flow to active tissues.

Adrenaline helps ensure working muscles get more blood by causing vasodilation in the arteries supplying them. It binds to beta-2 receptors on the smooth muscle of skeletal muscle arterioles, relaxing those vessels and lowering resistance. That increased diameter lets more blood flow to the muscles as they demand more oxygen and nutrients during exercise. At the same time, adrenaline shunts blood away from less-essential areas like the gut and skin by constricting their vessels, further prioritizing muscle perfusion. It also raises heart rate and the strength of each beat, boosting overall cardiac output to deliver the increased blood flow to active tissues.