HISTOLOGY
BLOOD VESSELS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Precapillary sphincters will
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control blood flow into the true capillaries
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cause blood to flow from the precapillary arteriole
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open when the tissue needs nutrients
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close when the tissue has low O2
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close when tissues have low CO2
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Explanation:
Detailed explanation-1: -Precapillary sphincters regulate the blood flowing into each capillary, and in times of greater oxygen demand, more precapillary sphincters will open in order to increase the amount of gas exchange occurring between the blood and tissues.
Detailed explanation-2: -Effect of Carbon Dioxide Carbon dioxide (CO2) has a profound and reversible effect on cerebral blood flow, such that hypercapnia causes marked dilation of cerebral arteries and arterioles and increased blood flow, whereas hypocapnia causes constriction and decreased blood flow [167, 168].
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