PATHOLOGY

Detailed explanation-1: -Arterioles. An arteriole is a very small artery that leads to a capillary. Arterioles have the same three tunics as the larger vessels, but the thickness of each is greatly diminished.

Detailed explanation-2: -Capillaries are small, thin blood vessels that connect the arteries and the veins. Their thin walls allow oxygen, nutrients, carbon dioxide and waste products to pass to and from the tissue cells.

Detailed explanation-3: -The vein that carries blood from organ to organ is called the portal vein. Portal vein begins from one organ as capillaries and ends in another organ as capillaries. Examples of such systems include the hepatic portal system, the hypophyseal portal system, and (in non-mammals) the renal portal system.