Describe the structure of a neuron with the help of a neat, labelled diagram.

The neuron is the functional unit of the nervous system and it consists of the following parts:

● CELL BODY- It is also known as cyton and is irregular in shape. Its extensions give rise to dendrites and axon as shown in the above diagram. It also contains a nucleus and granular substance called Nissel’s granules within it.

● DENDRITES- These are extensions of the cell body which are branched in nature. The function of these dendrites is to receive a stimulus and then transfer this stimulus to the cell body which further transfers the stimulus to complete nerve fibre.

● AXON- It is also an extension of nerve fibre which is very long and the nerve impulse transmits through this axon only. Ion channels are present in axon only which help in impulse transmission.

● AXON TERMINALS- This are branched endings of the axon which are also known as synaptic knobs because they are responsible for synapse and this knobs by secreting neurotransmitter helps in transmission of impulse through synapse from one neuron to the other.

● SCHWANN CELLS- Schwann cells are present over the axon and helps in formation of myelin sheath which prevents of leakage of current through the axon.

● NODES OF RANVIER- These are the sites where myelin sheath is absent and impulse transmission takes place through ion channels present over this nodes of ranvier.