Types of Neurons

Definition Of Neurons

A neuron is a specialised cell type in the nervous system responsible for receiving or transmitting biochemical signals in the body. Thus, giving them the potential to receive information, process it, and retransmit it to control sensory inputs, motor outputs, and cognitive functions. All three kinds of neurons work in concert to maintain a proper and integrated functioning of the nervous system.

There are three basic types of neurons: sensory neurons carrying signals from sense receptors to the central nervous system; motor neurons which convey commands from the central nervous system to muscles and glands; and interneurons which offer communication between the sensory and motor neurons within the CNS itself. All these kinds of neurons interact to maintain proper and integrated functioning of the nervous system.

Structure Of A Neuron

The different parts that make up a neuron to be a complete structure are stated below:

Description Of The Neuron Structure:

• Dendrites: The receiving extensions that receive the signals from other neurons and bring them to the cell body.

• Cell Body (Soma): Where the cell nucleus and organelles are found, and it is also where cellular processes happen along with the integration of the signal itself.

• Dendrite: Short branching projection, which carries the signal towards the cell body as input axon.

• Myelin Sheath: Fatty insulation over the axon that increases the rate of conduction.

• Synapse: Interface between the axon ending of one neuron and the dendrite or body of another neuron, where neurotransmitters are released to transmit the signal.

Classification Of Neurons

The classification of neurons is given below-

Based On Structure

• Multipolar Neurons: It has one axon and MANY dendrites and is mainly found in the brain and spinal cord. Perform complex activities such as motor control.

• Bipolar Neurons: These neurons have one axoN and one dendrite; they primarily participate in sensory functions for example vision and smell.

• Unipolar {Pseudounipolar) Neurons: They have one process that divides into two branches. Generally found in touch and temperature sensory paths.

Based On Function

• Sensory (Afferent) Neurons: They relay sensory information from receptors to the CNS. Electrically, action potentials arise in response to stimulation.

• Motor Neurons: They are efferent neurons, that transmit the signal from the CNS to the muscles or glands to elicit a response or act upon something.

• Interneurons: They are interconnecting neurons that remain inside the CNS. Their job is to connect sensory and motor neurons. They largely take part in reflexes and complex behaviours.

Detailed Description Of Each Neuron Type

The description of neurons is given below-

Sensory Neurons

• Function and Examples: The sensory neurons pick up stimuli from the surroundings and carry them in the form of electrical impulses. For example, neurons play a part in providing vision, hearing, and touch.

• Sensory Neurons: Sensory neurons relay the action potential from the sensory receptors towards the CNS through peripheral nerves, which are the site of processing.

Motor Neurons

• Function and Examples: Motor neurons transmit signals from the CNS to muscles and glands. Examples would be motor neurons controlling muscle contraction and the secretions of glands.

• Motor Neurons: They transmit signals from the CNS to the effector organs. Motor neurons give rise to physical action.

Interneurons

• Function and Examples: Interneurons communicate and process between the sensory and motor neurons, because they connect them within the central nervous system.

• Role in reflex arcs: The large responsibility of the interneuron is to pass the signals between sensory and motor neurons and reflex arc, because of which a very quick response is possible.

Specialised Neurons

The specialised neurons are given below-

• Purkinje Cells: Huge neurons with highly branched and elongated dendritic trees; they live in the cerebellum. They are involved in motor coordination and balance.

• Pyramidal Cells: Neurons whose cell bodies are pyramid-shaped and give off long axons. They are one of the classes of neurons involved in cognitive functions, such as learning and memory. They reside in the cerebral cortex.

• Mirror neurons: These are neurons that fire when a given action is performed by an individual and also in case the same action is witnessed in another thus involved in empathy and social understanding.

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