BIOL273 Study Guide - Final Guide: Ventricular Fibrillation, Heart Valve, Pacemaker Potential
31 Aug 2018
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Multicellular organisms need nutrients & o2 but cannot directly interact w/ external environment. Rate of diffusion of o2 + nutrients is limited by. Brain most oxygen dependant organ: 5-12 sec loss of consciousness, 5-10 min permanent brain damage by flow of blood, instead of diffusion distance, overcome by: cv system for transport of substances. Heart - functionally divided into 2 separate pumps that work in series. Pericardium = tough membranous sac surrounding the heart consist of 2 layers w/ a small amount of fluid between them that acts as a lubricant. Coronary arteries supplies blood to heart: heart has very high o2 demand depend on adequate blood flow entrance. Weak atrial contraction no valve at atrial. Semilunar valves - no cords to brace them b/c of their shape. Vasculature: inner lining - endothelium, elastic connective tissue, vascular smooth muscle. All 4 layers more elastic + smooth muscle. Endothelial + fibrous connective tissue (thin) assist in venous return.
