What is Neuron | what are the 3 types of Neuron?

Fig:Structure of Neuron. 


Neuron


The cells that transmit the message from one part of the body to the other are known as nerve cells or neurons.

They make the nervous tissue of the body. A neuron consists of three major parts: the cell body, the axon and the dendrites.

The cell body is round in shape and it is the centre of receiving and sending nerve impulses. From the cell body, two types of nerve fibres arise. They are dendrites and axon. The dendrites are highly branched and thin in structure. They receive impulses mostly from the axon of another neuron. The axon is a long and tube-like structure which also arises from the cell body. The axon may be covered with a medullary sheath. The axon along with the medullary sheath is called medullated nerve fibres. It sends most of the impulses to the dendrites of another neuron. The medullary sheath increases the speed of impulses along the axon.

The few neuron cell bodies outside the central nervous system are grouped into clusters called ganglia. The best known ganglia are in the autonomic nervous system. The nerves are actually the bundles of axons lying next to one another in a cord-like formation. They can be made up of the axons of motor neurons or sensory neurons or mixed neurons. The function of the nerve is to carry different impulses and it is performed by the following nerves.

# There are following three types of Neurons:

1. Afferent or sensory nerves: They carry impulses from various parts of the body to the brain or to the spinal cord.

2. Efferent or motor nerves: They carry impulses from the brain or the spinal cord to various parts of the body.

3. Mixed nerves: Sometimes, axons of both motor and sensory neurons form a nerve
which is called mixed nerve. All the spinal nerves are of mixed type.