This article explains what creates the electrical conditions that make it possible to generate electrical signals to transmit a signal within the neuron from one end to the other.

What creates the potential difference between the inside and outside of a neuron?

Basics:

Electric potential is the amount of electric potential energy per charge at a point.

V=U/q

V = electrical potential

U = electrical potential energy

q = charge

Electric potential difference or potential difference or voltage is the difference in electric potential between two points. A potential difference of 1 volt means that moving 1 unit of charge either requires or adds 1 joule of energy.

Answer:

Sodium-potassium pumps create this potential difference between the inside of the neuron and the outside of the neuron.

This pump actively transports:

Creating a net change of -1 inside the neuron relative to outside.

This process requires a lot of energy, which is provided in the form of ATP by the mitochondria (each cycle requires 1 ATP ). Neurons have a much higher number of mitochondria than other cells in the body because they need a continuous supply of energy to function. A large part of this energy is used by sodium–potassium pumps to maintain the resting membrane potential. Mitochondria are found throughout the neuron but there are dense clusters in nodes of Ranvier, soma, axon terminal.

Why do ions move from an area of higher concentration to an area of lower concentration?

This movement is due to the random motion of particles and probability.

Individual particles move randomly because of their kinetic energy. There is no force directing particles specifically from high to low concentration. The trend appears when there is a large number of particles due to statistics.

For example, imagine a 2D rectangle where:

The probability of individual particles moving in any of the left, right, top or bottom direction is 25% (each). About 25 particles move from right to left side and 2.5 particles will move from left to right. Even though movement is random, more particles will move from high concentration to low concentration.

So, no force moves particles from a higher to a lower concentration. 2nd law of thermodynamics (entropy always increases with time) and diffusion are the effects, not causes.

Why do Na⁺ ions move inside the neuron?

Na⁺ ions move into the neuron due to the electrochemical gradient, which has two components:

Electrical gradient

The inside of the neuron is more negative than the outside.

Chemical gradient
There is a higher concentration of Na⁺ ions outside the neuron than inside.

This is why Na⁺ enters the neuron when channels open.

Why does the action potential not begin in the soma?

The soma has relatively few voltage-gated Na⁺ channels.. This makes it difficult to open the required number of Na+ channels to initiate an action potential.

In contrast, the axon hillock (initial segment) has seven times as many Na+ ions as the soma. This makes it much easier to reach the threshold required to initiate an action potential.

As a result, action potentials typically begin at the axon hillock rather than the soma