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The Circulatory System The Heart and Blood Vessels Main Function To transport blood around the body along with the nutrients contained within the blood Example: oxygen Three Main Parts The Heart The Blood Vessels The Blood within the vessels Size and Location of Heart Avg size: 15 cm long, 9 cm wide Bordered laterally by lungs, posteriorly by spinal column, anteriorly by sternum Coverings Covered on surface by visceral pericardium which turns back on itself and becomes the parietal pericardium Made of dense CT, attaches to diaphragm, sternum, vertebral column, and large blood vessels emerging from heart Wall of the Heart Three distinct layers: Epicardium – outer layer that protects heart by reducing friction Serous membrane Myocardium – thick middle layer used to pump blood out of heart chamber Cardiac muscle tissue Endocardium – inner layer containing many elastic and collagenous fibers Also contains some blood vessels Chambers of the Heart Four chambers Two upper chambers: right and left ATRIA Thin walls, receive blood from returning to the heart Two lower chambers: right and left VENTRICLES Receive blood from atria, then contract to force blood out of the heart into arteries Septum – solid wall like structure that separates the right from the left side blood from right will never mix w/ blood from left Valves of the Heart Tricuspid valve – three cusps, lies between right atrium and right ventricle preventing backflow Strong fibrous strings attach to cusps and papillary muscles that are used to keep cusps from swinging back into atrium Pulmonary valve – allows blood to leave right ventricle and enter pulmonary trunk and prevents backflow Semilunar in shape Valves of the Heart cont. Bicuspid valve – two cusps, lies between left atrium and left ventricle preventing backflow Aortic valve – opens to allow blood to leave left ventricle and enter aorta Semilunar in shape Path of Blood Flow Heart Diagram LUNGS Vena Cava Pulmonary Artery Right Atrium Pulmonic Valve Septum Tricuspid Valve Right Ventricle Oxygenation of Blood in Lungs HEMOGLOBIN is a molecule in red blood cells that binds to oxygen Deoxygenated blood becomes oxygenated when hemoglobin picks up (binds to) oxygen in the lungs Oxyhemoglobin is bright red LUNGS Vena Cava Pulmonary Vein Aorta Pulmonary Artery Left Atrium Right Atrium Bicuspid Valve Aortic Valve Pulmonary Valve Septum Tricuspid Valve Left Ventricle Right Ventricle BODY So to review: Vena Cava Right Atrium Tricuspid Valve Right Ventricle Pulmonary Valve Pulmonary Artery Lungs Pulmonary Vein Left Atrium Bicuspid Valve Left Ventricle Aortic Valve Aorta Body