Initial rapid repolarization in cardiac muscle is mediated through:
Correct Answer: Opening of K+ channel
Description: Opening of K+ channel >> Closing of Na channel
The main factor is opening of K+ channel.
Although Ganong has maintained both closure of Na+ channels and opening of one type of K+ channel and closure of Na channel only,
The recent concept is K+ channel opening is the main reason of phase 1.
Phase 0 (depolarization), fast sodium channels open.
Phase 1 (initial repolarization), fast sodium channels close.
Phase 2 (plateau), calcium channels open and fast potassium channels close.
Phase 3 (rapid repolarization), calcium channels close and slow potassium channels open.
Phase 4 (resting membrane potential) averages about −90 millivolts.
Category:
Physiology
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