What is Action Potential?

The resting potential is a delicate balance. A signal from another neuron can introduce positive ions, causing the voltage to rise from -70 mV to -55 mV. This 'threshold' voltage triggers the opening of gated ion channels, akin to opening a floodgate.

Once gated ion channels open, positive sodium ions rush into the cell, creating a 'spike' in electrical potential. This process, called 'depolarization,' makes the inside of the cell more positively charged than the outside. The signal then propagates down the cell, similar to a 'wave' in a stadium.

After depolarization, the cell becomes highly positive due to the influx of sodium. The positive charge causes the gated ion channels to close. Ion pumps then work to expel excess sodium, causing the membrane potential to rapidly return to normal.

During repolarization, extra potassium channels open, leading to a brief 'hyperpolarization' where the electrical difference becomes even more negative than the resting state. The membrane then adjusts, and ion channels and pumps restore the normal resting membrane potential. This entire process occurs in less than a millisecond.

The video concludes by posing the question of how this signal transmits from one cell to the next, reserving the answer for the next episode, which will delve into the synapse.

Alie Astrocyte introduces the concept of action potentials, building upon the previous discussion of resting potential where the inside of a neuron has a negative charge. This video will explain how this resting potential transforms into a signal.