ANATOMY

Detailed explanation-1: -The tunica media or a middle layer composed of elastic and muscular tissue which regulates the internal diameter of the vessel. The tunic intima or an inner layer consisting of an endothelial lining which provides a frictionless pathway for the movement of blood.

Detailed explanation-2: -The tunica media is the middle portion of the vessel wall and contains smooth muscle cells and connective tissue, whereas the tunica adventitia is composed of connective tissue that is often continuous with the surrounding soft tissues.

Detailed explanation-3: -The tunica media is the thickest layer of the arterial wall and is composed of elastic fibers, SMCs, fibroblasts and extracellular matrix.

Detailed explanation-4: -Elastic arteries are those nearest the heart (aorta and pulmonary arteries) that contain much more elastic tissue in the tunica media than muscular arteries. This feature of the elastic arteries allows them to maintain a relatively constant pressure gradient despite the constant pumping action of the heart.

Detailed explanation-5: -Specifically in arteries, vasoconstriction decreases blood flow as the smooth muscle in the walls of the tunica media contracts, making the lumen narrower and increasing blood pressure. Similarly, vasodilation increases blood flow as the smooth muscle relaxes, allowing the lumen to widen and blood pressure to drop.