An Action Potential — An Explanation

Action potential is reached at the Axon Hillock of the axon. A change in membrane potential of ~15–20 mV is sufficient to cause the propagation of an Action Potential. The action potential in a particular neuron occurs as follows.

1. Resting membrane potential = -70 mV
2. Summation of graded potentials cause a depolarisation of roughly 15–20 mV at the axon hillock.
3. Na+ ion-channels open, causing the influx of Na+ ions.
4. As the Na+ ions flow in, the K+ ion-channels open, allowing the influx of K+ ions.
5. The change in membrane potential from 0 — +40 mV is called the overshoot.
6. At +40 mV, the Na+ ion-channels close. Lowering the membrane potential
7. At 0 mV, the K+ ion-channels close.
8. The dipping of membrane potential below -70 mV is known as undershoot.

All Action Potentials are roughly 2 ms

All Action Potentials have amplitude of -70 — +40 mV