Structural unit of the nervous system is the nerve cell or neuron. Neuron is highly specialised cell. Neurons carry impulses or messages. New nerve cells are not produced to replace the damaged or destroyed nerve cell. A neuron has three parts. They are
1. cyton
2. axon and
3. dendrites
1. The cyton:
1. It is also called the cell body.
2. It has a large and round nucleus.
3. In the cytoplasm of the cyton, nissl granules are present.
2. Axon:
1. It is the long and cylindrical process that arises from the cyton.
2. In some nerve cells, axon is surrounded by a layer of fatty material known as myelin sheath.
3. The myelin sheath is not continuous throughout length of the axon.
4. It is broken at regular intervals.
5. These broken spots are called as nodes of Ranvier.
3. Dendrites: Arise from the cyton they are much branched, when compared to axon.
