PATHOLOGY

Detailed explanation-1: -The arteriolar lumen regulates the flow of blood through the capillaries. Venules are the smallest veins and receive blood from capillaries. They also play a role in the exchange of oxygen and nutrients for water products.

Detailed explanation-2: -Tunica Intima Until recently, the endothelium was viewed simply as the boundary between the blood in the lumen and the walls of the vessels. Recent studies, however, have shown that it is physiologically critical to such activities as helping to regulate capillary exchange and altering blood flow.

Detailed explanation-3: -Blood Vessels: Circulating the Blood Through the thin walls of the capillaries, oxygen and nutrients pass from blood into tissues, and waste products pass from tissues into blood. From the capillaries, blood passes into venules, then into veins to return to the heart.