Short notes on the structure of a neuron

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Short notes on the structure of a neuron

Also called nerve cells, the neurons constitute the basic struc­tural unit of the nervous tissue. Each neuron is made up of three parts namely the cyton, dendrites and axon.

(i) Cyton:

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This is also called the cell body, soma or perikaryon. Body of the neuron may be rounded, oval, or stellate. The cytoplasm is abundant and it is called neuroplasm. The cyton has a large nucleus with a distinct nucleolous. The cytoplasm also has mitochondria golgi aparatus, flat glob­ules and fine thread like structures called neurofribrils.

There is no centrosome so that the neuron cannot divide. But some zoologists opine that centrosomes are present in the neurons. In addition to this the cytoplasm has numerous basophilic bodies called Nissle’s granules. The exact func­tioning of these granules is not understood. But they seem to play an important role in the metabolism of the neurons as indicated by the fact that they undergo changes under different physiological conditions. Elec­tron microscopic studies of the Nissle’s granules have shown it to be rough endoplasmic reticulum.

(ii) Dendrites:

These are small minute processes that arise from the cyton. They show a high degree of branching. The function of these dendrites is to connect one neuron with the another.

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(iii) Axon:

This is a single long process that arises from the cyton. It is usually given off from the small conical region of the cyton which is known as axon hillock or implantation cone. The cone contains ribo­nucleic acid, protein and iron. The axon at its free end gives rise to minute branches called telodendrites. The cytoplasm of the axon is known as axoplasm.

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