Dr Manju Antil (Counselling Psychologist and Psychotherapist)

The human brain has about 86 billion neurons, according to a recent study (Herculano-Houzel, 2009). Unlike other cells, which can divide or regenerate after death, these cells complete their development around the time of birth.

How do Neurons Work?

Neurons are located near each other but are not connected. A synapse is a very small space between neurons. A neuron's function is to transmit nerve impulses along the length of the neuron and across the synapse into the next neuron. Neurons transmit electrical signals known as action potentials.

For the electrical signal to continue travelling to or from the CNS, it must pass the synaptic gap. Chemicals that diffuse between the two neurons are used for this. Neurotransmitters are the name for these substances.

During synaptic transmission, the action potential (an electrical impulse) causes the presynaptic neuron's synaptic vesicles to release neurotransmitters (a chemical message).

These neurotransmitters go across the synaptic gap (the space between pre- and post-synaptic neurons) and attach to specialised receptor sites on the post-synaptic neuron. This will cause an electrical impulse to be sent to the next cell.

These information-processing neurons are found in both the peripheral nervous system, which is made up of sensory and motor nerve cells and the central nervous system, which includes the brain and spinal cord.

Parts of a Neuron

The soma (cell body) of the neuron is where the axon (a nerve fibre carrying electrical impulses away from the soma) and dendrites extend (tree-like structures that receive signals from other neurons). A protective coating called the myelin sheath surrounds the axon and speeds up the transmission of nerve impulses along the axon.

The synapse, which separates the axon of one neuron from the dendrite of the following neuron, prevents neurons from touching one another. The special structure of neurons enables them to take in and transmit messages to neighbouring neurons as well as throughout the body.

Dendrites

The tree-root-shaped dendrites, which are often shorter and more numerous than axons, are a component of the neuron. They serve as information receivers from other neurons and transmitters of electrical impulses to the cell body. Because dendrites are coated in synapses, they may pick up messages from other neurons. While some have longer dendrites, other neurons have shorter ones. Neurons in the central nervous system are lengthy and have intricate branching structures that enable them to receive information from several other neurons. For instance, in order to receive signals from thousands of other cells, Purkinje cells, which are located in the cerebellum, have extremely developed dendrites.

Essentially, the soma, or cell body, is the centre of the neuron. The soma's role is to sustain the cell and ensure that the neuron continues to operate properly (Luengo-Sanchez et al., 2015). A membrane surrounds the soma, protecting it while yet enabling interaction with its immediate environment. A cell nucleus found in the soma creates genetic data and controls protein synthesis. The function of other components of the neuron depends on these proteins.

Axon: The axon, also known as a nerve fibre, is a tail-like component of the neuron that connects to the cell body at a point known as the axon hillock. The purpose of the axon is to send electrical messages to other neurons by carrying impulses from the cell body to the terminal buttons. Most neurons only have one axon, which can range in size from 0.1 millimetres to over 3 feet (Miller & Zachary, 2017). Myelin, a fatty material that coats certain axons, insulates the axon and speeds up the signal transmission. Axons are lengthy nerve processes that can branch off to send messages to various locations before coming to a stop at synapses.

Myelin Sheath

The axons of neurons are protected by a layer of fatty tissue called the myelin sheath. Its main function is to act as a barrier between different nerve cells, preventing interference between the impulses coming from different neurons. Accelerating the conduction of nerve impulses along the axon is the myelin sheath's secondary role. The myelin sheath is made up of glial cells, which are sometimes referred to as oligodendrocytes and Schwann cells, and the axons that they encase.

To insulate and safeguard the axon, the myelin coating that covers these neurons is present. This shielding makes it possible for neurons to communicate with one another far more quickly than unmyelinated neurons can.