MICROANATOMY

Detailed explanation-1: -The venous system is a lower-pressure system, containing veins that have larger lumens and thinner walls. They often appear flattened.

Detailed explanation-2: -Arteries have smaller lumens than veins, a characteristic that helps to maintain the pressure of blood moving through the system. Together, their thicker walls and smaller diameters give arterial lumens a more rounded appearance in cross section than the lumens of veins.

Detailed explanation-3: -(LOO-men) The cavity or channel within a tube or tubular organ such as a blood vessel or the intestine.

Detailed explanation-4: -Arteries are more muscular and have smaller, rounder lumens (internal spaces) than veins. The artery lumen has a wavy endothelium, or inner lining, due to the configuration of elastic tissue beneath it.

Detailed explanation-5: -The two largest veins in the body are the superior vena cava, which carries blood from the upper body directly to the right atrium of the heart, and the inferior vena cava, which carries blood from the lower body directly to the right atrium.