Answer:
The sequence of shifts in the electrical charge of a neuron is called Action Potential.
Explanation:
An action potential occurs when a neuron sends information down an axon, away from the cell body. Neuroscientists also use the terms, spike or impulse.
An Action Potential takes place in four steps:
Step 1:
Certain chemicals like neurotransmitters bind to dendrites and open special channels called stimulus gated channels.
Step 2:
Here comes depolarization in which neuron undergoes a shift in charge distribution.Charge reaches -59 mV. Positive sodium ions move into the cell and neuron becomes less negative(positive).
Step 3:
Repolarization occurs when the charge reaches a certain limit( 30 mV). Na+ channels stop and K+ channels open resulting in K+ ions moving out of the cell to make the neuron negatively charged again.
Step 4:
Hyperpolarization: K+ ions floods back at such a speed that a charge of -75 mV is reached for a very short period of time before resting potential is reached again.
Here, a neuron is at resting potential when it is not sending messages.
Action potential is the state in which a neuron sends messages down the axon away from the cell body. Action Potential fires when depolarization reaches -55 mV.
