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Roddilla · Sep 25, 2011, 01:45 AM

During exercise or a lot of activity we know that heart rate increases. Sympathetic neurons also stimulate arteries and veins to change shape. My question is which arteries and veins dilate and which constrict? During exercise do arteries leading to muscles dilate so that more blood volume reaches them? But of they dilate won't speed decrease?

Fr_Chuck · Sep 25, 2011, 04:02 AM

You have been asked ( please don't require me to make it a formal warning) that we do not DO you home work for you, but require you to put some effort as to telling us why you think a answer is a certain way, we will then help you find the right direction.

As all experts are TOLD not to merely give you an answer.

So to begin why do you think it is so ? Which ones do you think it may be

Roddilla · Sep 25, 2011, 04:17 AM

I think that arteries should neither constrict nor dilate since by dilating volume increases but speed decreases and on constricting speed increases and volume decreases. This is according to the Physics Equation: A1V1 = A2V2 where A is area and V is velocity.

Unknown008 · Sep 25, 2011, 08:06 AM

Actually, they do dilate. Another factor which comes in is that the heart will pump more, faster. This results in an increase in pressure and an increase in the volume of blood entering the vein/artery.

Also, veins don't really dilate/constrict. They dilate/constrict depending on the pressure of the blood. They can dilate and become surprisingly large if the pressure is high (much bigger than a thumb ;) ). It's just like when the blood pressure is high, the blood will push on the vein to make it larger.