Action Potentials - Laboratory in Principles of Physiology | BMS 302, Study notes of Biology

Download Action Potentials - Laboratory in Principles of Physiology | BMS 302 and more Study notes Biology in PDF only on Docsity! 20 March Action Potentials Slow response Pacemakers SA node AV node Ectopic foci (can depolarize but are not SA or AV node) Prepotential (pacemaker potential) ↑ Ca++ influx ↑ Na+ influx (through leakage channels) ↓ K+ efflux Depolarization: Ca++ influx through voltage gated channels Repolarization: K+ efflux through voltage gated channels Fast response Atrial muscle Ventricular muscle Bundle of His Bundle branches Purkinje fibers Resting membrane potential: leakage channels Depolarization: Na+ influx through voltage gated channels Plateau phase: Ca++ movement inward balances K+ movement outward through voltage gated channels Repolarization: K+ efflux through voltage gated channels Measuring electrical activity Extracellular recording of electrical activity of heart Electrocardiogram Provides the following information Conduction disturbances Presence of ischemic damage Orientation of the heart in the thorax Mass of cardiac muscle: hypertrophy Electrical effects of drugs and electrolytes Cannot provide information about Mechanical or contractile properties Voltage meter detects differences between two electrodes Left depolarizing and right at rest Left surface is negative with respect to right Voltage meter reading = negative Left repolarized and right still at rest No difference between left and right Voltage meter reading = 0 Left repolarized and right depolarizing Left surface is positive with respect to right Voltage meter reading = positive Waves and Intervals P wave – atrial depolarization QRS complex – ventricular depolarization