Cardiac Arrhythmias: Difference between revisions

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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===
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