Question

Which of the below is most likely to result in relaxation of smooth muscle upon an arteriole?

a. release of norepinephrine from SNS neurons near the arteriole

b. a blood clot in an artery that blocks blood flow into the tissue

c. a need to vasoconstrict that arteriole

Please explain why! Thanks!

Answer 1

The question talks about the relaxation of smooth muscles of arteriole i.e. vasodilation.

So we basically have to look for the factors that can lead to vasodilation. Let's check each option one by one-

Option a.-Norepinephrine being a part of the sympathetic nervous system leads to vasoconstriction (to increase the blood pressure).

Option b.-A clot in the arteriole will lead to the compromise of the blood supply to the tissues distal to the clot,that will lead to ischemia of the tissue,and remember ischemia is on of the most important stimulators of vasodilation (so that the lumen size of the arteriole increases and the blood may reach the dying tissue ).

Option C- vasoconstriction will lead to contraction of the smooth muscles and that is not what we intend to do.

So the correct answer is b.