Presentation on theme: "Lab and Lecture Notes. Location Thoracic cavity between two lungs ~2/3 to left of midline surrounded by pericardium: Fibrous pericardium- "— Presentation transcript:
Lab and Lecture Notes
Location Thoracic cavity between two lungs ~2/3 to left of midline surrounded by pericardium: Fibrous pericardium- Inelastic and anchors heart in place Inside is serous pericardium- double layer around heart Parietal layer fused to fibrous pericardium Inner visceral layer adheres tightly to heart Filled with pericardial fluid- reduces friction during beat.
Heart Wall Epicardium- outer layer Myocardium- cardiac muscle Two separate networks via gap junctions in intercalated discs- atrial & ventricular Networks- contract as a unit Endocardium- Squamous epithelium lines inside of myocardium
Chambers 4 chambers 2 upper chambers= Atria Between is interatrial septum Contains fossa ovalis- remnant of foramen ovalis 2 lower chambers = ventricles Between is interventricular septum Wall thickness depends on work load Atria thinnest Right ventricle pumps to lungs & thinner than left
Great Vessels Of Heart- Right Superior & inferior Vena Cavae Delivers deoxygenated blood to R. atrium from body Coronary sinus drains heart muscle veins R. Atrium Tricuspid Valve R. Ventricle pumps through Pulmonary Trunk R & L pulmonary arteries lungs
Great Vessels Of Heart-Left Pulmonary Veins from lungs oxygenated blood L. atrium Bicusid (Mitral) Valve Left ventricle ascending aorta body Between pulmonary trunk & aortic arch is ligamentum arteriosum fetal ductus arteriosum remnant
Valves Designed to prevent back flow in response to pressure changes Atrioventricular (AV) valves Between atria and ventricles Right = tricuspid valve (3 cusps) Left = bicuspid or mitral valve Semilunar valves near origin of aorta & pulmonary trunk Aortic & pulmonary valves respectively
Blood Supply Of Heart Blood flow through vessels in myocardium = coronary circulation L. & Right coronary arteries branch from aorta branch to carry blood throughout muscle Deoxygenated blood collected by Coronary Sinus (posterior) Empties into R. Atrium
Conduction System 1% of cardiac muscle generate action potentials= Pacemaker & Conduction system Normally begins at sinoatrial (SA) node Atria & atria contract AV node -slows AV bundle (Bundle of His) bundle branches Purkinje fibers apex and up- then ventricles contract
Pacemaker Depolarize spontaneously sinoatrial node ~100times /min also AV node ~40-60 times/min in ventricle ~20-35 /min Fastest one run runs the heart = pacemaker Normally the sinoatrial node
Electrocardiogram Recording of currents from cardiac conduction on skin = electrocardiogram (EKG or ECG) P wave= atrial depolarization Contraction begins right after peak Repolarization is masked in QRS QRS complex= Ventricular depolarization Contraction of ventricle T-wave = ventricular repolarization Just after ventricles relax
Cardiac Cycle after T-wave ventricular diastole Ventricular pressure drops below atrial & AV valves open ventricular filling occurs After P-wave atrial systole Finishes filling ventricle (`25%) After QRS ventricular systole Pressure pushes AV valves closed Pushes semilunar valves open and ejection occurs Ejection until ventricle relaxes enough for arterial pressure to close semilunar valves
Action Potential Review muscle Heart has addition of External Ca 2+ creates a plateau prolonged depolarized period. Can not go into tetanus.