PATHOLOGY MCQ
BLOOD VESSELS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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constrictslocal arterioles, thereby increasing pressure and increasing local bloodflow
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stimulates precapillarysphincters and decreases local blood flow
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dilateslocal arterioles, thereby increasing pressure and increasing localblood flow
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constrictsprecapillary sphincters and thereby increases local blood flow.
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Detailed explanation-1: -Smooth muscles in the walls of arteries can contract or relax to cause vasoconstriction (narrowing of the lumen of blood vessels) or vasodilation (widening of the lumen of blood vessels).
Detailed explanation-2: -If the precapillary sphincters dilate, blood flows in the true capillaries and contributes to the exchange with the tissue cells. If the precapillary sphincter contracts, blood flows into the metarteriole and the thoroughfare channel, bypassing the true capillaries and the cells.
Detailed explanation-3: -This is called the precapillary sphincter. The precapillary sphincter has now also been found in the brain, where it regulates blood flow to the capillary bed. The sphincter can open and close the entrance to the capillary, by which contraction causes blood flow in a capillary to change as vasomotion occurs.