HSCI 100 Lecture Notes - Lecture 9: Heart Valve, Pulmonary Vein, Varicose Veins
20 Apr 2016
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Document Summary
What is the main pathway of blood in the body: heart arteries arterioles capillaries venules veins back to the heart . Oxygenated blood (carrying o2) is shown in red, deoxygenated is shown in blue. Arteries and arterioles: carry blood away from the heart, their walls have 3 layers: Outer connective tissue: arterioles are small arteries that regulate blood pressure. Constrict to control how much blood goes to an area. Capillaries: microscopic vessels between arterioles and venules, made of one layer of epithelial tissue, form beds of vessels where exchange with body cells occurs. Carbon dioxide diffuse into the capillary: create large surface area. Veins that carry blood against gravity have valves to keep blood flowing toward the heart and prevent backflow. Weakening of these valves and enlargement of the veins, with blood pooling up in them leads to varicose veins. Your skeletal muscles also help to push" blood back to the heart.
