Action potential


Nerve signals travel along action potential which is rapid changes in membrane potential that spread rapidly along the nerve fiber membrane called electrical neural impulse.

It has three stages

  • Resting stage

  • Depolarization

  • Repolarization

Resting: Membrane is already polarized because of -90 millivolts negative membrane potential.

Depolarization: Membrane suddenly becomes permeable to sodium ions which allows positive ions to enter the axon. -90 is now neutralized  to zero. It then overshoots to +35.

Repolarization: At repolarization stage  sodium channels close  and potassium channels open  allowing potassium ions to move outside the axon thereby re-establishing normal negative resting membrane potential called repolarization.

Other channels such as the voltage-gated sodium and potassium channels are involved in action potential. The action potential generated is then propagated along the axon and distributed as electrical signals to distance axons. For propagation is guided by the 'all or nothing principle.' There is also the safety factor for propagation of action potential.


Brainstem Thalamus Forebrain Medulla Midbrain Pons
Temporal lobe Basal ganglia Epithalamus Cerebral operculum Remove operculum Wall of lateral ventricle 1
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