Blood Vessels

• the veins are the blood vessels that carry deoxygenated blood back to the heart from the body
• the artery is a blood vessel that distributes oxygen-rich blood around the body
• capillaries are the smallest blood vessels in the circulatory system. They transport blood, nutrients and oxygen to cells in your organs and body systems
• collagen is the main structural protein in the body, it is found in tendons, ligaments, bones, and skin
• smooth muscle is a type of muscle that contracts without control of the nervous system and is made of a thin form of layers
• arterioles are a very small blood vessel that connects arteries to capillaries and carries blood away from the heart
• venules are the smallest veins and carry blood from the capillaries to the heart
• the artery has a thick muscular layer and a thick layer of elastic fibres, a narrow lumen and a thick wall, more collagen and no valves
• vein has a thinner muscular layer than an artery, less elastic tissue, wider lumen, thinner walls with more collagen and valves
• capillaries have extremely thin walls to allow for exchange of materials between blood and tissues, no collagen, no valves, no smooth muscle or elastic fibres, and a lumen diameter of 5-10 micrometres
• pressure = force/area
• blood pressure is the force exerted by blood on the walls of vessels as it flows through them
• veins always carry blood away from the heart
• arteries always carry blood towards the heart
• veins carry oxygenated blood (aside from the pulmonary artery)
• arteries carry deoxygenated blood (except for the pulmonary vein)
• veins carry blood under high pressure
• arteries carry blood under low/negative pressure
• veins have connective tissue which provides strength
• elastic fibres allow the vessels to stretch and recoil
• smooth muscles allow the walls to constrict and dilate
• collagen is a tough, fibrous protein to make the walls of blood vessels strong and durable