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AAMC 9 vs Wiki

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km1865

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So theres a questoin on AAMC 9 asking which of hte following is common to arteries, veins and capillaries.. The correct answer is that all of these vessels are lined with endothelial cells. that's fine, but just curious to know more about the answer choice that says ability to actively dilate or constrict regulating blood flow.. According to the explanation only arteries have thick muscular walls capable of vasodilation/vasoconstriction.. however wiki says "Vasodilation refers to the widening of blood vessels[1] resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins"

So veins ARE or ARE NOT capable of vasodilation or vasoconstriction?!

Thanks!
 

paul411

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which of hte [sic] following is common to arteries, veins and capillaries.. The correct answer is that all of these vessels are lined with endothelial cells. that's fine, but just curious to know more about the answer choice that says ability to actively dilate or constrict regulating blood flow.. According to the explanation only arteries have thick muscular walls capable of vasodilation/vasoconstriction

Capillaries cannot actively dilate/contract. So the option talking about dilating/constricting does not apply to capillaries (only to veins and arteries). You have to pick the option which applies too all three: arteries, veins and capillaries. The correct option is the presence of endolitheal cells.

Vasodilation refers to the widening of blood vessels[1] resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large arteries, smaller arterioles and large veins

Wikipedia is correct. There is nothing contradictory or erroneous is this excerpt.

So veins ARE or ARE NOT capable of vasodilation or vasoconstriction?!

Veins are capable of vasodilation and vasoconstriction.
 

neurodoc

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Capillaries cannot actively dilate/contract. So the option talking about dilating/constricting does not apply to capillaries (only to veins and arteries). You have to pick the option which applies too all three: arteries, veins and capillaries. The correct option is the presence of endolitheal cells.

Correct



Wikipedia is correct. There is nothing contradictory or erroneous is this excerpt.



Veins are capable of vasodilation and vasoconstriction.

Again, correct. This explains the clinically useful pharmacologic interventions that can change PRELOAD (i.e. "venous") vascular capacitance or AFTERLOAD (i.e. systemic arterial capacitance)
 

tn4596

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so you both saying that aamc 9 is wrong?
all i know is that the smooth muscle in vein is used to move the blood. vasoconstriction and vasodilation is used during sympathetic and parasympathetic responses to enhance/limit oxygenated blood flow to certain tissues. Vein only carry blood away from these tissue so why would they be able to? I also checked Campell and Reece, altho they did not mention that vein cannot vasodilated/vasoconstrict, they only associated these function to arteries/aterioles.
 

paul411

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^ No. Both AAMC 9 and Wiki are correct. They key point here is that capillaries don't constrict/dilate whereas veins, arteries and arterioles can.
 

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