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Human Anatomy and Physiology Cardiovascular physiology Design Pulmonary circuit Artery and vein Blood to and from lungs Systemic circuit Blood to tissues Heart design Three dimensional hollow mass of muscle Double pump 2 receiving chambers - atria 2 pumping chambers - ventricles Fibrous skeleton Suspended in fluid filled pericardial sac Heart Anatomy 4 chambers AV valves Tricuspid Bicuspid - mitral Semilunar valves Right - pulmonary Left - aortic Inferior view of valves Heart Anatomy Pericardium Heart wall (epicardium, myocardium, endocardium) Heart wall Coronary circulation Arteries arise from base of aorta Venous blood empties into the right atrium Coronary disease 1. Angina pectoralis Temporary halt in blood delivery 2. Myocardial infarction Amitotic myocardium Scar tissue formed is non-contractile Conduction pathway Muscle cells modified to conduct electrical information (myogenic pacemaker) Autorhythmical cells SA node AV node Bundle of His Bundle branches Purkinje branches Conduction pathway Excitation sequence Conduction pathway Heart rate fluctuations Sympathetic Cardiac nerve Norepinephrine (Na+, Ca++ influx) Parasympathetic Vagus nerve Acetycholine (K+ efflux) Potentials in conductive pathway Na+ permeability Potentials in conductive pathway Potentials in conductive pathway Refractory period Skeletal muscle - short Cardiac muscle - long Refractory period What causes it? Electrocardiograph Irregular heartbeats SA node fires early Extra heartbeat followed by a pause Force of contraction Time Ectopic pacemaker AV node taking over role of damaged SA node Slower heartbeat No P wave Ventricles with greater contractility Irregular heartbeat Heart block: blockage of conductive pathway Slower heartbeat Multiple P waves Irregular QRS Fibrillation Continuous disorganized AP pattern APs with decreased refractory period Cure: defibrillate with high voltage causes simultaneous refractory period Cardiac cycle • Systole/diastole • Mid-to-late diastole • Atria and ventricles relaxed • Ventricles fill 80% • AV valves open, aortic & pulmonary valves closed • SA node discharge • EDV Cardiac cycle • Ventricular systole • QRS complex • AV valves close • 1st. heart sound • Isometric pressure build up • Aortic and pulmonary valves open • ESV • Atrial pressure rises • Aortic pressure rises • T wave • AV valves open, pulmonary and aortic valves close • 2nd. heart sound (dicrotic notch) Cardiac cycle • Early diastole • Atria fill with blood • AV valves open • Remember the aortic and pulmonary valves are closed Heart sounds • Lub • Turbulent blood flow as a result of closure of AV valves • Onset of systole • Dub • Turbulent blood flow as a result of closure of aortic and pulmonary valves • Onset of diastole Heart murmurs • Common in children • Adults: irregular turbulent flow through valves • Stenosis: narrow valve opening • Regurgitation: leakage of blood through a valve Summary Ion movement Heart sounds Pressure changes causes valves to open and close Electrical activity Muscle contraction