If capillaries don't have muscles then how can they contract and expand during vasoconstriction and vasodilation ??? 

Asked by noorhashmiaf | 20th Jan, 2021, 11:10: AM

Expert Answer:

Vasoconstriction is narrowing or constriction of the blood vessels. It happens when smooth muscles in blood vessel walls tighten. The opposite of vasoconstriction is vasodilation. This is when blood vessels relax and widen, increasing blood flow and dropping blood pressure.

Answered by Sheetal Kolte | 20th Jan, 2021, 11:41: AM