Answer:
Blood vessels receive multiple messages, but the two best known are vasodilation and vasoconstriction.
Explanation:
Blood vessels are vasodilated in infectious diseases or in strokes where the adjacent tissue is swollen and this vasodilation is needed for cellular migration of the cells of the immune response, this vasodilation is mediated by chemical mediators such as nitric acid.
On the other hand, in situations where the vessels are injured, the endothelial cells expose surface factors, and histamine is released so that a strict and temporary vasoconstriction is triggered in the injured vessel to prevent hemorrhage.
These are the two most important vessel responses that are regulated by chemical mediators such as nitric acid and histamine.
