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CARDIAC MUSCLE-ACTION POTENTIAL

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CARDIAC MUSCLE-ACTION POTENTIAL

1. Resting membrane potential = -90mV (intracellular space negative compared to extracellular space).

2. This resting potential is affected by K+ in the extracellular space.

3. Note the 4 phases of cardiac action potential (AP):
- Phase 0: initial rapid depolarization & overshoot due to opening of voltage gated Na channels, similar to skeletal
- Phase 1: initial rapid repolarization due to closure of Na channels
- Phase 2: prolonged plateau due to slower but prolonged opening of voltage gated Ca channels
- Phase 3: final repolarisation to resting membrane potential due to closure of Ca channels and efflux of K


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REFERENCES

1. Mcminn. (2003). Last's Anatomy. Elsevier Australia. ISBN:0729537528. Read it at Google Books - Find it at Amazon
2. Netter, F. H. (2019). Atlas of human anatomy. Philadelphia, PA: Elsevier.
3. Image: no reference available.

Ⓒ A. Manickam 2018

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