nm825

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I'm very confused as to what causes arterioles to skeletal muscle to vasodilate during exercise. I've read that it's from local metabolite buildup in the muscles during exercise. If this is the case, then what's even the point of have B2 receptors on vessels going to skeletal muscle? Why would you need them if the arterioles are just going to vasodilate when they need to?

Also, Constanzo writes, "(1) In the circulation of the skin, splanchnic regions, kidney, and inactive muscles, vaso- constriction occurs via a1 receptors, which results in increased resistance and decreased blood flow to those organs. (2) In the exercising skeletal muscle, however, local metabolic effects override any sympathetic vasocon- stricting effects, and arteriolar vasodilation occurs."

Why would the local metabolic effects need to "override" anything? The sympathetic system would be dilating those arterioles via B2 receptors not constricting them. What is she talking about here?
 
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OnePunchBiopsy

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I was taught that Beta-2 andrenergic receptors in skeletal muscle blood vessels lead to vasodilation. I think local metabolites are also do their part, but it is mostly autonomics at play.
 

DrPicard

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Resting skeletal muscle is under autonomic control, when exercising it becomes auto-regulatory.
 
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DrPicard

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Just to add, the sympathetic nervous system acts primarily on alpha-1 receptors, not beta-2. beta-2 is the main target for blood borne epinephrine.