A typical neuron consists of two parts. Cell bodies and neurites.
1. Cell body: The cell body is the main part of a neuron. It may appear round, oval, star-shaped, triangular, pointed or triangular in shape. Its diameter is 5-120 micrometers. It consists of plasma membrane, cytoplasm and nucleus. Cytoplasm of neuron is called neuroplasm. Neuroplasm contains mitochondria, Golgibodies, neurofibrils, ribosomes, endoplasmic reticulum, lysosomes, glycogen and numerous Nisal granules. Polyribosomes join to form Nisal granules. Nisal seeds produce protein.
2. Neurite: Branches arising from the cell body are called neurites. It is of two types. namely
(i) Axon: The unbranched long-tube neurites arising from the cell body are called axons. The site from which the axon originates is called the hilocum. Each axon is covered by neurolemma. Between the axon and the neurolemma is the myelin sheath or medullary sheath. Myelin sheaths are formed from Swan cells. The area of the axon where there is no myelin sheath is called the segment of Ranvier. The branches that emerge from the side of the axon are called collateral branches. The end of the axon divides into tiny branches. These are called telodendria. The bulge at the end of the telodendria is called the synaptic knob or terminal button.
Inside the axon are microtubules, neurofilaments, mitochondria, lysosomes etc. Its length is more than 1 millimeter.
(ii) Dendrites: The small branches formed from around the cell body are called dendrites. Dendrites contain ribosomes, smooth endoplasmic reticulum, neurofilaments, etc. It transmits the impulse to the cell body.