Elasticity Of Arteries
Arteries carry blood away form the heart the extremities and organs. They have typical three layer blood vessel wall structure with a thick tunica media. The walls of arteries are highly compliant due to the elastic fibres present. The wall thickness of the arteries varies in based on the proximity to the heart. The elasticity of arteries allows pressure absorption from the left ventricle of the heart as it pumps blood into the arteries. There are two significant types of arteries, elastic and muscular. Elastic arteries are the largest in the body and include the aorta and pulmonary trunk. The vessel walls are relatively thin in comparison to the overall size. They assist in propelling blood onwards while ventricles are relaxing by storing
mechanical energy when they are stretched and releasing kinetic energy back into the blood when they recoil. Allowing the blood to continue moving through the arteries even while the ventricles are relaxed. Muscular arteries contain more smooth muscle and fewer elastic fibres. The significant number of smooth muscle cells make the walls relatively thick. The loose structure allows changes in diameter to take place, assisting in vasodilation and vasoconstriction to adjust the rate of blood flow.
Veins carry deoxygenated blood back to the heart from the organs and extremities. The size of veins varies depending on the proximity to the heart; the closer they are, the larger they are. Veins range in size from approximately one millimetre to three centimetres, with very thin walls relative to their diameter. They have a typical three layer wall structure with a thick tunica externa. They are distensible enough to adapt to the variation in volume and pressure of blood passing through them however they are not designed to withstand large amounts of pressure as the average blood pressure in veins is lower than that of arteries. Many veins contain valves that assist in venous return by preventing the back flow of blood. Veins are more numerous that arteries and are often paired to accompany small and medium sized muscular arteries. Superficial veins form anastomoses with deep veins that travel between skeletal muscles. The connection allows communication between deep and superficial blood flow.
mechanical energy when they are stretched and releasing kinetic energy back into the blood when they recoil. Allowing the blood to continue moving through the arteries even while the ventricles are relaxed. Muscular arteries contain more smooth muscle and fewer elastic fibres. The significant number of smooth muscle cells make the walls relatively thick. The loose structure allows changes in diameter to take place, assisting in vasodilation and vasoconstriction to adjust the rate of blood flow.
Veins carry deoxygenated blood back to the heart from the organs and extremities. The size of veins varies depending on the proximity to the heart; the closer they are, the larger they are. Veins range in size from approximately one millimetre to three centimetres, with very thin walls relative to their diameter. They have a typical three layer wall structure with a thick tunica externa. They are distensible enough to adapt to the variation in volume and pressure of blood passing through them however they are not designed to withstand large amounts of pressure as the average blood pressure in veins is lower than that of arteries. Many veins contain valves that assist in venous return by preventing the back flow of blood. Veins are more numerous that arteries and are often paired to accompany small and medium sized muscular arteries. Superficial veins form anastomoses with deep veins that travel between skeletal muscles. The connection allows communication between deep and superficial blood flow.