The Neuron | Nerve Cell | (Structure Overview)
A nerve cell is a basic unit of our nervous system. Neurons are nerve cells found in the nervous system.
It consists of three parts :
1. Cell body – it contains nucleus surrounded by cytoplasm and cell organelles,
2. Dendrites (from Greek ‘dendron’ meaning tree) – highly branched extension coming out from one side of the cell body. Function of dendrites is to receive an impulse from other cell at synapses and transmit it to the cell body.
3. Axon – cylindrical projection coming out on the other side of the cell body. Axon carries the nerve impulse away from cell body and towards next nerve cell or muscle fiber.
Axon contains cytoplasm called axoplasm and plasma membrane called axolemma.
Axons are insulated by multilayers of myelin sheath which is produced by Schwann cells, named after German physiologist Theodor Schwann who discovered them, surrounding the axon.
This myelin sheath is not continues, it has gap in between and that is called node of Ranvier, named after Louis Antoine Ranvier.
The end of axon is termed as axon terminal which ends with synaptic end bulbs which contains neurotransmitters in sacs.
The gap between two neurons or a neuron and muscle fiber is called synapse where the neurotransmitters will be released and gives signal to the next cell.
Learn about Cells, Tissues, Organs & Systems – Levels of Organization here.