Summary ANATOMY OF BLOOD VESSELS AND TISSUES

Blood Vessels • Blood vessels are the components of the circulatory system that transport blood containing nutrients and oxygen to the tissues of the body. • They also takes waste and carbon dioxide away from the tissues. Five classes of blood vessels 1. Arteries 2. Arterioles 3. Veins 4. Venules 5. Capillaries. • Blood vessels are arranged into three concentric/circular layers or tunics • The three layers (tunics) are; 1. Tunic intima/interna • Has simple squamous epithelium surrounded by a connective tissue basement membrane with elastic fibers. 2. Tunic media • Is primarily the thickest smooth muscle layer • It not only provides support for the vessel but also changes vessel diameter to regulate blood flow and blood pressure. 3. Tunic externa • Is a fibrous connective tissue with varying amounts of elastic and collagenous fibers that attaches the vessel to the surrounding tissue Arteries • They are blood vessels that deliver oxygen-rich blood, nutrients and hormones from the heart to the tissues and cells of the body • All arteries carry oxygenated blood– except for the pulmonary artery • Each artery is a thick –walled muscular tube, lined by thick smooth muscle layer in tunica media that makes them handle the high pressures from the heart. • The largest artery in the body is the aorta   2 types of arteries; i) Elastic: They contain larger numbers of collagen and elastic tissue in their tunica media than muscular arteries do, giving them the ability to stretch in response to each pulse • They are located close to the heartAorta ii) Muscular: Have more smooth muscle than elastic arteries e.g Femoral, radial e.t.c