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Name: Derick C Mather
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Question:
In order for a giraffe brain to get blood the pressure must be high. What happens then when it lowers his/hers head to drink. One would almost think that they would blow the top of their heads off.



Replies:
Really the same thing that happens to you when you raise or lower your head. The arteries serving your heart (carotids) constrict when you lower your head, and that lowers the blood pressure reaching the head. When you raise it, they dilate, raising the pressure. Sometimes this doesn't work very well, and you feel dizzy when you suddenly raise your head. If this is severe, you may faint, which is a very efficient way of putting your head back below your heart.

--ProfBill



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