Describe the vessel wall characteristics of the five main types of blood vessels that blood travels through from the time it leaves the left ventricle until it returns to the right atrium

Question

What will be an ideal response?

Answer 1

Blood is carried away from the heart in arteries. All arteries have an outer tunica externa (mostly elastic and collagen fibers), an inner tunica media (mostly smooth muscle and elastic fibers) and a lining called the tunica interna (endothelial tissue). Large diameter arteries have more elastic fibers than smooth muscle in their walls and conduct blood to regions of the body, e.g. the subclavian artery carries blood toward the upper extremity. As arteries enter a body region, they branch and their diameters decrease. Their walls have proportionately more smooth muscle than elastic tissue. These arteries are called muscular or distributing arteries, e.g. the radial artery. Branching of the blood vessels continues until the vessels are nearly microscopic arterioles. Arterioles have little elastic tissue, but can change diameter quickly because of the smooth muscle in their wall. Thus, they are the major sites of regulation of blood pressure and distribution. Arterioles feed into capillary beds. Capillaries are the sites of exchange between the tissues and the blood. Venules drain the capillaries and begin the path back to the heart. Venules merge to form veins (and ultimately, vena cava) that carry the blood to the heart. Veins have much less smooth muscle than arteries. Vein also have valves that help prevent backflow of blood.