Question

In reference to vasoconstriction and vasodilation, they are

• A. terms that denote the speeding up or slowing down, of pulse rate.
• B. an important means of regulating blood flow through blood vessels.
• C. accomplished strictly by neural input from the sympathetic nervous system.
• D. the primary mechanisms by which the nervous system controls the heart’s forces of contraction.

Answer 1

The correct option is B

an important means of regulating blood flow through blood vessels.

Arteries and arterioles have their own tiny smooth muscles that can constrict or dilate (causing vasodilation) depending on CO₂ concentrations. When we breathe more, our arterial CO₂ levels lower, blood vessels constrict and vital organs (like the brain, heart, kidneys, liver, stomach, spleen, colon, etc.) get less blood supply. Similarly, hypocapnia causes spasm of all other smooth muscles of the human body: airways or bronchi and bronchioles, diaphragm, colon, bile ducts, etc.When you get a small bleeding cut or a wound, deliberately hyperventilate and see if that can help stop the bleeding. It should, due to vasoconstriction.