What is action potential

 An action potential is a rapid sequence of changes in the voltage across a membrane. The membrane voltage, or potential, is determined at any time by the relative ratio of ions, extracellular to intracellular, and the permeability of each ion. In neurons, the rapid rise in potential

What are the phases of action potential

1. Stimulus artifact
2. Latent period
3. Slow depolarization
4. Firing level
5. Rapid depolarization
6. Spike potential
7. Rapid repolarisation
8. Slow repolarisation
9. Hyperpolarisation
1. Stimulus artifact – A brief irregular deflection of the baseline at the beginning of recorded AP. It marks the point of stimulus.
      2. Latent period – the period between the application of stimulus and the beginning ofaction potential. This is the time taken by  the impulse to travel along the axon.
       3. Slow depolarization – This is due to Na+ influx through the sodium leakage channels.
4. Firing level – The point at which the rate of depolarization increases.
5. Rapid depolarization – This is due to rapid entry of Na+ through voltage gated Na+ Channels.
6.    Spike potential – The sharp rise and rapid fall are the spike potential of the axon.
7.  Rapid repolarization – This is due to rapid exit of K+  through the voltage gated K+ channels.
       8. After depolarization – a slower fall of potential at the end of repolarisation. This is due to slow exit of K+
 9. After Hyperpolarization – Overshooting of tracing in the hyperpolarizing direction. This is due to continuous efflux of K+ through                    slow K+ channels.

What is ionic potential

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