Neurons are functional units of nervous system.
Neurons is a cell that transmits nerve impulses.
Nervous system contains over 100 billion nerve cells or neurons which are specialized to transmit impulses from one part of body or CNS to another.
Parts of Neuron
1. Cell body
2. Axon (single axon)
3. Dendrites
1. Cell body
Cell bodies varies size and shapes. They are too small to be seen by nacked eye.
Cell body contains nucleus and other cell organelles.
Cell body has large nucleus which contains nucleolus that are responsible for the metabolism, growth and repair of Neuron.
Cell body consist -
nissle bodies (RER and free ribosome)
endoplasmic reticulum
lysosome
mitochondria
neurofilaments
golgi bodies
Cell body connects to dendrites which bring information into the neuron and axon which send the information to other neurons.
Cell body form grey matter of the nervous system and are found at the PNS of brain and in the center of spinal cord.
Cluster of cell bodies in central nervous system called nuclei.
Cluster (group) of cell bodies in peripheral nervous system called ganglion.
Bundle of neuron are called tracks in CNS and nerves in PNS.
2. Dendrites
Dendrites are branches of neurons that receive signals from other neurons, the signals go to the cell body.
Dendrites conduct nerve impulses towards cell body.
Dendrites of short, branches, extension of cell bodies that receives stimuli.
A neuron may have many as 200 dendrites.
Dendrites form grey matter of Nervous System.
3. Axons
Each nerve cell has only one axon. Axon carries impulses away the cell bodies.
Axon form white matter of the central nervous system.
Axons found deep in the brain and are in groups. They are called tracks, on the other hand found in PNS is called nerves, they are referred to as nerves or nerves fibers outside the brain and spinal cord.
Note - Grey matter consist of cell bodies, dendrites and unmyelinated axons.
White matter consist of myelinated axons.
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