NEURONS

A neuron or also called nerve cell processes and transmits information through signals called electrical and chemical signals .Neurons connect to each other and form networks called neural networks. Neurons are the core components of the brain. They are also the spinal cord of the central nervous system. The main features that define neurons are electrical excitability and the presence of synapses which are some complex membranes that transmit signals to other cells. There are 3 parts of a typical neuron. They are: soma or cell body, dendrites and axon. There are no neurons as such that lack soma. But there are neurons which lack dendrites and sometimes also axon.

Neurons are highly specialized for the processing and transmission of cellular signals.

The soma is the body of neuron, as it contains nucleus most protein synthesis occurs here. The nucleus can range from 3 to 18 micrometers in diameter. Whereas the soma of a neuron can vary from 4 to 100 micrometers in diameter.
The dendrites of the neuron are the extensions with many branches. This is where the majority of the input to the neuron occurs.
The axon is a cable like structure that extends hundreds of times the diameter of the soma in length. The axon carries nerve signals away from soma and some information back to it. The part of axon where it emerges from soma is called the axon hillock. This region also receives input from other neurons.
The soma is usually about 10-25 micrometers in diameter and is often not larger than the cell nucleus that it contains.


The average human brain has about 100 billion neurons. Each neuron may be connected to up to 10,000 other neurons, passing signals to each other. The human brain’s memory capacities vary wildly from 1 to 1000 terabytes. Unlike other body cells, most of the neurons in the human brain are able to divide to make new cells through a process called neurogenesis during foetal development and even for a few months after birth. Until the age of 18 these brain cells may increase in size and they are essentially designed to last a lifetime. The pulse rapidly travels along the cell’s axon. The connection between neurons is not static even though they change over time. The greater the signals between 2 neurons, the stronger the connection grows. Each axon contains thousands of membrane-bound sacs known as vesicles, which in turn contains many neurotransmitter molecules each. The 2 most common neurotransmitters in the brain are the amino acids glutamate and GABA.


The neurons vary in size from 4 microns(.004mm) to 100 microns(.1mm) in diameter.
Unlike most other cells, neurons can’t re-grow after damage. But there is an exception for the neurons present in hippocampus.
Neuralgia meaning nerve glue, are a type of brain cell. These cells guide neurons during foetal development.