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Cardiac Arrhythmias: Difference between revisions
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→Phase 0: Rapid Depolarization
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[[File:AP.png|thumb|500px|'''Figure 1.''' The cardiac ventricular action potential and relevant ion channels.]] | [[File:AP.png|thumb|500px|'''Figure 1.''' The cardiac ventricular action potential and relevant ion channels.]] | ||
===Phase 0: Rapid Depolarization=== | ===Phase 0: Rapid Depolarization=== | ||
Rapid depolarization is started once the membrane potential reaches a certain threshold (about -70 to -60 mV). This produces a rapid influx of Na<sup>+</sup> and a rapid upstroke of the action potential. At higher potentials (-40 to -30) Ca<sup>2+</sup> influx participates in the upstroke. In the sinus node and AV node a slower upstroke can be observed (Figure 2). This is because the rapid depolarization in these cells is mainly mediated by the slower acting Ca<sup>2+</sup> ion channels. The slower activation produces a slower upstroke. | Rapid depolarization is started once the membrane potential reaches a certain threshold (about -70 to -60 mV). This produces activation of sodium channels and a rapid influx of Na<sup>+</sup> and a rapid upstroke of the action potential. At higher potentials (-40 to -30) Ca<sup>2+</sup> influx participates in the upstroke. In the sinus node and AV node a slower upstroke can be observed (Figure 2). This is because the rapid depolarization in these cells is mainly mediated by the slower acting Ca<sup>2+</sup> ion channels. The slower activation produces a slower upstroke. | ||
===Phase 1: Early Rapid Repolarization=== | ===Phase 1: Early Rapid Repolarization=== | ||