Nervous Impulse- How Does The Internal WhatsApp Work? The term nerve impulse refers to the signal that is being transmitted from one body part to the other.
In technical terms, a nerve impulse can be defined as a wave of electrochemical changes that travel along the length of a neuron.
In this blog, the actual system of nerve transmission will be briefly explained.
And how our body conducts signals of infinite impulses a day.
Generation And Transmission Of Nerve Impulse
Before learning about the transmission of nerve impulses, we need to discuss the term “membrane potential”, which refers to the capacity to do the electrical work, that exists on neuron membrane.
Membrane potential is exhibited in two forms, Resting membrane potential, and active membrane potential.
Resting Membrane Potential/ Polarized State
This state is characterized by the positive outer surface and the negative inner surface of the neuron membrane.
In this state, the neuron is supposed to be at rest and the polarized state is expressed as -70 mV.
The negative sign refers to the negativity present inside the neuron.
In this state, the membrane is not stimulated or conducting impulses.
Distribution Of Ions- Inside And Outside The Neuron
The concentration of Potassium ions is greater inside the membrane and the concentration of sodium ions is greater outside the membrane.
These ions are continuously moved against their concentration gradient through sodium-potassium pumps.
For every two molecules of potassium that are pumped inside, three molecules of sodium are pumped outside.
This is the reason why the inside membrane is negative compared to the outside membrane.
Negative Organic Ions
Organic compounds present inside the neurons hold a negative charge.
These ions include amino acids, many proteins, and RNA.
The presence of negative ions also contributes to the negativity of the inner membrane.
Leakage Of Potassium Ions
The cell membrane has many channel proteins called gates.
Potassium ions continuously leak through these gates and this is another reason why the inside of the neuron membrane is more negative than the outside.
Active Membrane Potential/ Depolarized State
This state is characterized by a positive inner membrane than the outside.
And negative outer membrane than inside.
This happens when the neuron receives a stimulus (signal) and the positive charges tend to move inside.
This change appears for a brief period of time, followed by the recovery of the polarized state.
Influx Of Sodium Ions
When a neuron is stimulated, it causes the opening of sodium gates.
As a result, sodium gates permit the entrance of sodium ions by diffusion.
The potential of the membrane changes from -70 mV to zero, then reaches 50 mV.
This state lasts about one millisecond till the sodium gates are not closed.
Repolarization Of Neuron Fibre
Depolarization of the axon membrane causes potassium gates to open.
Potassium, therefore, diffuses out of the cell.
And the neuron returns to its polarized state, this stage is known as repolarization.
Nervous Impulse- How Does The Internal WhatsApp Work? After an action potential, the nerve fiber undergoes a period of recovery, meaning it regains the original distribution of ions.
Although the repolarized neuron fiber has the same polarity, it has different ionic distribution.
In this stage, the original ionic distribution is restored by the sodium-potassium pump.
This returns the membrane to its resting potential, -70mV.