Structure of Neuron

Neurons contain three basic parts

1. A cell body

The cell body has a large,  central nucleus.

2. Dendrites

The extensions of cell body that conduct nerve impulse (signals) towards the cell body. The motor neurons has many thread-like dendrites.

3. Axons

The extensions that conducts signals away from the cell body are called axons. The axons are relatively long & cylindrical.

Following structures are also present in neurons

Myelin sheath

The laminated lipid sheath around the neurons is called myelin sheath. It covers axons of neuron. Sometimes , it also covers dendrites.

The neurons of hydra and sea anemones do not have myelin sheath.

Other invertebrates & vertebrates have sheathed neurons..

Schwann cell


Schwann cells are present in some neurons. They wrap the myelin sheath in the layers. Some gaps are left in these neurons. These gaps are called nodes of Ranvier (neurofibril nodes). These nodes make the myelin sheath segmented at regular intervals. The neurolemmocyte also helps in the regeneration of injured myelinated neurons.

Comparison of nervous system & neurons

The nervous system receive data ( input stimulus). It integrates. It produces a output response in living organisms body physiology. Thus we can say that the dendrites of neurons act as receptors. The cell body acts as integrator and ends of the axons are the effectors.

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