Stages of Action Potential1) Resting State2) Threshold 3) Depolarization Phase of Action Potential4) Repolarization Phase of Action Potential5) Undershoot6) Back to Resting StateAction Potential – Voltage-gated Ion ChannelsAction Potential 1. Resting StateStages of Action Potential1) Resting State – Both sodium and potassium channels are closed and membrane is in the resting state.2) Threshold 3) Depolarization Phase of Action Potential4) Repolarization Phase of Action Potential5) Undershoot6) Back to Resting StateAction Potential 2. ThresholdStages of Action Potential1) Resting State2) Threshold - A stimulus opens some Na+ channels. If the influx of Na+ achieves threshold, then more channels are opened, triggering an action potential. 3) Depolarization Phase 4) Repolarization Phase of Action Potential5) Undershoot6) Back to Resting StateAction Potential 3. DepolarizationStages of Action Potential1) Resting State2) Threshold 3) Depolarization Phase- Activation gates of sodium channels are open, but the potassium channels remain closed. Sodium ions rush into the cell, the interior of the cell becomes more positive.4) Repolarization phase of action potential5) Undershoot6) Back to Resting StateAction Potential 4. RepolarizingStages of Action Potential1) Resting State2) Threshold 3) Depolarization Phase-4) Repolarization phase- Inactivation gates close sodium channels, and potassium channels open. Potassium ions leave the cell, and the loss of positive charge causes the inside of the cell to become more negative.5) Undershoot6) Back to Resting StateAction Potential 5. UndershootStages of Action Potential1) Resting State2) Threshold 3) Depolarization Phase4) Repolarization phase5) Undershoot - Both gates of the sodium channels are closed, but potassium channels remain open because their relatively slow gates have not had time to respond to repolarization of the membrane. Within another millisecond or two, the resting state is restored and the system is ready to respond again. 6) Back to Resting StateAction Potential – Voltage-gated Ion