The Cardiovascular System - The Heart.docx - The...

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The Cardiovascular System: The HeartHeart AnatomyThe Pulmonary and Systemic CircuitsHeart is a transport system consisting of two side-by-side pumpsRight side receives oxygen -poor blood from tissuesPumps blood to lungs to get rid of CO2, pick up O2, via pulmonary circuitLeft side receives oxygenated blood from lungsPumps blood to body tissues via systemic circuitReceiving chambers of heartRight AtriumReceives blood returning from systemic circuitLeft AtriumReceives blood returning from pulmonary circuitPumping chambers of heartRight ventriclePumps blood through pulmonary circuitLeft ventricle Pumps blood through systemic circuitSize and LocationApproximately the size of a fistWeighs less than 1 poundLocationIn mediastinum between second rib and fifth intercostal spaceOn superior surface of diaphragmTwo-thirds of heart to left of midsternal lineAnterior to vertebral column, posterior to sternum
Coverings of the HeartPericardium: double-walled sac that surrounds heat; made up of two layersSuperficial fibrous pericardium:functions to protect, anchor heart to surrounding structures, and prevent overfillingDeep two-layered serous pericardiumParietal layer lines internal surface of fibrous pericardiumViscerallayer (epicardium) on external surface of heartTwo layers separated by fluid-filled pericardial cavity (decrease friction)Three Layers of Heart WallEpicardium:visceral layer of serous pericardiumMyocardium: circular or spiral bundlesof contractile cardiac muscle cells Cardiac skeleton: crisscrossing, interlacing layer of connective tissueAnchors cardiac muscle fibers Supports great vessels and valvesLimits spread of action potentialsEndocardium:innermost layer; is continuous with endothelial lining of blood vesselsLines heart chambers and covers cardiac skeleton of valvesChambers and Associated Great Vessels Internal featuresFour chambersTwo superior atriaTwo inferior ventriclesInternal septum:separates atriaFossa ovalis:remnant of foramen ovale of fetal heartInterventricular septum:separates ventriclesSurface featuresCoronary sulcus (atrioventricular groove)Encircles junction of atria and ventricles
Anterior interventricular sulcusAnterior position of interventricular septumPosterior interventricular sulcusLandmark on posteroinferior surface Atria: the receiving chambersSmall, thin-walled chambers; contribute little to propulsion of bloodAuricles:appendages that increase atrial volumeRight atrium:receives deoxygenated blood from bodyThree veins empty into right atrium:1.Superior vena cava:returns blood from body regions above the diaphragm2.Inferior vena cava:returns blood from body regions below the diaphragm3.Coronary sinus:returns blood from coronary circulationLeft atrium:

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