Action potential

Action Potential Propagation

• Definition of Action Potential

  • An action potential is a rapid and temporary change in the membrane potential of a neuron, depicted graphically as a red band.

• Directionality of Propagation

  • Action potentials are propagated in one direction along the axon. This directional flow is crucial for efficient communication within the nervous system.

• Change in Membrane Potential

  • During the process of an action potential, the inside of the cell membrane becomes positively charged relative to the outside. This means there is a significant change in the electrical gradient across the membrane.

• Local Currents Generation

  • The action potential generates local currents. These local currents are responsible for:
  • Depolarizing the Adjacent Membrane: The local currents tend to increase the membrane potential of the areas immediately adjacent to the action potential.

• Threshold and New Action Potential Generation

  • When the depolarization from these local currents reaches a specific level known as the threshold, it triggers a new action potential in the adjacent segment of the axon. This is critical for the continuation of the nerve impulse along the axon.

• Refractory Period

  • The propagation of an action potential occurs unidirectionally due to the refractory period:
  • Absolute Refractory Period: This is the period immediately following an action potential when the previously depolarized area of the membrane cannot generate another action potential.
  • The presence of this refractory period ensures that the action potential travels in only one direction along the axon, preventing backward propagation.