3 Location Thoracic cavity between two lungs surrounded by pericardium: ~2/3 to left of midlinesurrounded by pericardium:Fibrous pericardium-Inelastic and anchors heart in placeInside is serous pericardium- double layer around heartParietal layer fused to fibrous pericardiumInner visceral layer adheres tightly to heartFilled with pericardial fluid- reduces friction during beat.
5 Heart Wall Epicardium- outer layer Myocardium- cardiac muscle Two separate networks via gap junctions in intercalated discs- atrial & ventricularNetworks- contract as a unitEndocardium- Squamous epitheliumlines inside of myocardium
9 Chambers 4 chambers 2 upper chambers= Atria Between is interatrial septumContains fossa ovalis- remnant of foramen ovalis2 lower chambers = ventriclesBetween is interventricular septumWall thickness depends on work loadAtria thinnestRight ventricle pumps to lungs & thinner than left
10 Great Vessels Of Heart- Right Superior & inferior Vena CavaeDelivers deoxygenated blood to R. atrium from bodyCoronary sinus drains heart muscle veinsR. Atrium Tricuspid Valve R. Ventriclepumps through Pulmonary TrunkR & L pulmonary arteries lungs
11 Great Vessels Of Heart-Left Pulmonary Veins from lungsoxygenated bloodL. atriumBicusid (Mitral) Valve Left ventricleascending aorta bodyBetween pulmonary trunk & aortic arch is ligamentum arteriosumfetal ductus arteriosum remnant
15 Valves Designed to prevent back flow in response to pressure changes Atrioventricular (AV) valvesBetween atria and ventriclesRight = tricuspid valve (3 cusps)Left = bicuspid or mitral valveSemilunar valves near origin of aorta & pulmonary trunkAortic & pulmonary valves respectively
21 Blood Supply Of HeartBlood flow through vessels in myocardium = coronary circulationL. & Right coronary arteriesbranch from aortabranch to carry blood throughout muscleDeoxygenated blood collected by Coronary Sinus (posterior)Empties into R. Atrium
26 ElectrocardiogramRecording of currents from cardiac conduction on skin = electrocardiogram (EKG or ECG)P wave= atrial depolarizationContraction begins right after peakRepolarization is masked in QRSQRS complex= Ventricular depolarizationContraction of ventricleT-wave = ventricular repolarizationJust after ventricles relax
28 Cardiac Cycle after T-wave ventricular diastole Ventricular pressure drops below atrial & AV valves open ventricular filling occursAfter P-wave atrial systoleFinishes filling ventricle (`25%)After QRS ventricular systolePressure pushes AV valves closedPushes semilunar valves open and ejection occursEjection until ventricle relaxes enough for arterial pressure to close semilunar valves
29 Action Potential Review muscle Heart has addition of External Ca2+ creates a plateauprolonged depolarized period.Can not go into tetanus.