How action potentials propagate down the axon

Action potentials are the electrical signals that allow neurons to communicate with each other. 

• Let’s delve into how these fascinating events propagate down an axon:

Depolarization and Na+ Channels:

At the start of an action potential, the membrane potential of the neuron depolarizes due to the opening of voltage-gated Na+ channels.

As more Na+ channels open, the Hodgkin cycle kicks in, leading to the regeneration of the action potential.

This sequential process causes the action potential to move down the axon.

Propagation Down the Axon:

The propagating action potential depolarizes the axon segment in front of it, bringing it to threshold.

Once the threshold is reached, this segment generates its own action potential.

The process repeats as the action potential travels along the axon, like a wave of depolarization1.

Refractory Period and Unidirectional Propagation:

The refractory period plays a crucial role in ensuring unidirectional propagation.

After an action potential, an area of the membrane remains refractory, preventing the action potential from moving backward.

This ensures that the signal travels only in one direction along the axon1.

Myelination and Saltatory Conduction:

Myelin, a fatty substance, wraps around some axons.

Myelination decreases membrane capacitance and increases resistance, resulting in less current loss during propagation.

The action potential “jumps” from one Node of Ranvier (unmyelinated region) to the next, a process called saltatory conduction.

This leads to faster propagation speeds compared to non-myelinated axons1.

In summary, the coordinated opening and closing of ion channels, refractory periods, and myelination all contribute to the efficient and precise propagation of action potentials in neurons.🌟