Question

Explain multiple mechanisms for how a tissue that has increased metabolic activity will gain increased blood flow.

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Answer 1

There are multiple mechanisms by which the blood flow to the metabolically active tissues will increase. Here are some of the mechanisms as follows: -

i) When there is increase in the metabolic activity within the tissues, there is increase in the local arteriolar vasodilation. The local arterioles tend to widen due to the vasodilation due to the relaxation of the smooth muscle cells that are localized within the vessel walls. When such vasodilation takes place, it enables increase movement of the blood into the tissues. Due to the increase cardiac output and reduction in the vascular resistance, there is increase in the blood flow through the vessels.

ii) When the metabolic activity of a tissue is increased, it would have higher demand for oxygen and hence it would lead to increase in the movement of the blood flow into the tissues due to the increased requirement of the oxygen.

iii) Another mechanism is through active hyperemia in which there is increase in the flow of blood into the metabolically active tissues due to the increase in the vasoactive metabolites. There is increase in the synthesis of the vasodilatory agents during the active metabolism period and this leads to increase in the flow of blood into these tissues.