Arteries, Capillaries & Veins Essay Example | Topics and Well Written Essays - 750 words

Arteries, Capillaries & Veins - Essay Example To enable this function the walls of the arteries are made of three separate layers consisting of elastic tissue, smooth muscle, and collagen or connective tissue. (2). This structure of the artery allows it to expand and contract, and it is this pulsating feature of the arteries that enables blood to reach every part of the body in combination with the pumping action of the heart. Arteries expand to receive the blood pumped from the heart and contract to push it forward into the tissues and organs. (1). The smooth muscle fibers that cause the expansion and contraction of the artery are under the control of the sympathetic nervous system and so the expansion and contraction of the arteries are coordinated by the sympathetic nerves. (2). In essence, the function of the arteries is to transport blood away from the heart to the other parts of the body and the blood transported consists of oxygenated blood, except for the pulmonary artery. (2). The capillaries are very narrow blood vessels. Their diameter is about 5-20 micrometers. Nearly all the tissues in the body possess a network of capillaries. The walls of the capillaries only one cell thick and it is this feature that enables the function of the capillaries to exchange of material between the capillaries and the surrounding cells of the tissue. The capillaries receive blood from the arteries to perform their function of exchange of material required for the functional activity of the various tissues and organs in the body. Once the exchange has occurred the capillaries pass on the blood to the venues. (2). The narrowness of the capillaries causes the individual blood cells to pass as a single file to enable the exchange of essential requirements of the surrounding tissue like oxygen and nutrients into the tissue and the removal of materials like carbon dioxide and waste materials from the tissue. This activity makes up the function of the capillaries.