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Physiology

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Nerve Muscle Physiology

Question
1 out of 19
 

Muscle's blood supply increases during exercise due to - (AIPG 2009)



A Increased blood pressure

B Accumulation of active metabolites

C Increase vasodilatation

D Increase heart rate

Ans. B Accumulation of active metabolites

The most important factor responsible for the increased blood flow in the exercising muscles is local; there is accumulation of metabolites which open up the precapillary sphincters, thereby recruiting more capillaries into circulation.

a. The tremendous increase in muscle blood flow that occurs during skeletal muscle activity is caused primarily by chemical effects acting directly on the muscle arterioles to cause dilatation.

b. One of the most important chemical effects is reduction of oxygen in the muscle tissues. That is, during muscle activity, the muscle uses oxygen rapidly, thereby decreasing the oxygen concentration in the tissue fluids. This in turn causes local arteriolar vasodilatation both because the arteriolar walls cannot maintain contraction in the absence of oxygen and because oxygen deficiency causes release of vasodilator substances.

c. These local metabolites include lactate, adenosine, substance P etc, also p4, low pO2, high CO2 andincreased temperature results in vasodilation.

d. The most important vasodilator substance is probably adenosine in heart.

Nerve Muscle Physiology Flashcard List

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