Question
Action potential in cardiac muscles is due to which ions‑
| A. |
K+
|
| B. |
Na+
|
| C. |
Ca+
|
| D. |
Cl-
|
Show Answer
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Correct Answer � B
Explanation
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|
Ans. b > a & c
- Na+, K+, and Ca+, all are involved in full cycle of action potential in cardiac muscle.
- But, the main phase (phase 0 or depolarization) is due to Na+ ions.
- Phase 0 (phase of rapid depolarization) → opening of fast sodium channels with Na+ influx.
- Phase 1 (initial phase of rapid repolarization) –> closure of fast sodium channels.
- Phase 2 (plateau phase) → opening of voltage-gated slow Ca++ channels with calcium influx.
- Phase 3 (final repolarization) → opening of K+ channels with efflux.
- Phase 4 –> Resting membrane potential.
