Discuss the effect of exercise on arterial stiffness and vascular aging - Essay Example

The outermost layer of blood vessels is made up of connective tissue. The elastin and collagen fibers in this outermost layer allow the blood vessels to stretch and recoil, and absorb tensile stress, respectively. The middle layer contains smooth muscle fibers and extracellular matrix, which also contains collagen and elastion. Finally, the innermost endothelial layer is a single layer of flattened cells that minimizes resistance to blood flow (Campbell and Reece, 2002, p. 877). Capillaries, which are deep-seated in tissues, have thin walls to allow supplies delivered by arterial blood to diffuse to the surrounding tissues, and at the same time, to permit cellular wastes to dissolve into the blood that will subsequently go through the veins.

Once in the veins, the blood is now deoxygenated. The veins lead to the kidneys and lungs where wastes and carbon dioxide are released, respectively. Upon entering the lungs, the blood is again infused with oxygen to be delivered to the systemic tissues of the body. Because of their function, arteries are thickened and more muscular than veins and capillaries. The thick muscles allow them to absorb a lot of tensile stress the pressure from the oxygenated blood pumped by the heart brings. When the heart contracts (systole) and blood flows through the arteries, the narrow openings of the artery into the arterioles leading to the capillaries temporarily traps blood inside the vessels, applying pressure onto the arterial walls.

When the heart relaxes, the elastic arterial walls relax back to their initial diameter, pushing the blood into the arterioles (diastole). However, the heart contracts again before blood can completely flow out of the arteries Campbell and Reece, 2002, p. 878-879). The thickness of arterial walls is a function of increased number and or activity of myocytes, endothelial cells, and connective tissues comprising the blood vessels. For example, shear stress brought about by increased blood flow velocity