Atrial Fibrillation_fall 2012

Rapiddepolarizationof atrialandventricular tissue

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Unformatted text preview: tside Primarily determined by difference in ion concentrations (Na+ and K+) between inside and outside of cell Cardiac Action Potential Cardiac Action Potential Phase 0 – Rapid depolarization of atrial and ventricular tissue – Rapid influx of Na+ – Membrane potential reaches ~ +20 mV Cardiac Action Potential Cardiac Action Potential Phase 1 – Brief initial repolarization – Inactivation of fast Na+ channels – Cl­ influx and/or K+ efflux – Membrane potential nears 0 mV Cardiac Action Potential Cardiac Action Potential Phase 2 – Plateau – Ca2+ influx – Balanced by K+ efflux – Membrane potential remains fairly constant Cardiac Action Potential Cardiac Action Potential Phase 3 – Rapid repolarization – K+ efflux – Moves cell back to RMP Cardiac Action Potential Cardiac Action Potential Phase 4 – Resting membrane potential – Na+ efflux and K+ influx – Eventually leads up to Phase 0 Absolute Refractory Period Absolute Refractory Period Period of time during which cardiac tissue cannot be stimulated to generate another action potential – Cannot be depolarized u...
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This note was uploaded on 06/01/2013 for the course ECON 2301 taught by Professor Lipsh during the Fall '12 term at Broward College.

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