ACTION POTENTIAL:
Phase o: Cell is stimulated, cell menbrane is more permeable to sodium ions.
Phase 1: Brief period of rapid repolarization: sodium influx ends in fast channels: potassium flows out
Phase 2: Plateau phase: influx of calcium and sodium through slow channels which sometimes occurs in Phase 0 and Phase 1: Respondible for the refractory period during whic the depolarized stae is maintained. Calcium’s role is related to the contractility of the heart.
Phase 3: Negativity restored due to increased loss of intracellular potassium.
Phase 4: Return to resting membrane potential (-90 mV). Normal distribution of Na+ and K+ are restored.
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