PATHOLOGY

Detailed explanation-1: -The heart is a muscular pump that provides the force necessary to circulate the blood to all the tissues in the body. Three layers of the heart are: the epicardium, the myocardium, and the endocardium.

Detailed explanation-2: -Vasoconstriction is the narrowing (constriction) of blood vessels by small muscles in their walls. When blood vessels constrict, blood flow is slowed or blocked. Vasoconstriction may be slight or severe. It may result from disease, drugs, or psychological conditions.

Detailed explanation-3: -Arteries and arterioles have relatively thick muscular walls because blood pressure in them is high and because they must adjust their diameter to maintain blood pressure and to control blood flow.