Final answer:
The sympathetic ANS shunts blood from non-essential organs to muscles by increasing heart rate, breathing rate, and constricting blood vessels in non-essential organs while dilating vessels in skeletal muscles, aided by the release of norepinephrine and hormones like epinephrine from the adrenal medulla.
Step-by-step explanation:
The sympathetic division of the autonomic nervous system (ANS) uses several mechanisms to shunt blood from organs to muscles during the fight-or-flight response. This includes increasing the heart rate and breathing rate, and the constriction of blood vessels in non-essential organs. Concurrently, blood vessels in skeletal muscles dilate, allowing for increased blood flow to these priority areas.
Neural mechanisms involve the release of norepinephrine from postganglionic sympathetic fibers and hormones from the adrenal medulla—epinephrine and norepinephrine—that bind to adrenergic receptors in the blood vessel walls, causing vasoconstriction in non-essential organs and vasodilation in skeletal muscles.
Additionally, the hormonal component of the sympathetic response, mainly the secretion of epinephrine and norepinephrine into the bloodstream, ensures that the response is swift and affects multiple organ systems simultaneously, facilitating the shunting of blood towards skeletal muscles.