Know The Hardware - I (Nervous System)

Neuron

Neurons (also called nerve cells) are the primary cells of the nervous system. They are found in the brain, the spinal cord, in the peripheral nerves and ganglia.  The neuron is the basic unit of information processing and the building block of the brain. Working together with other neurons and cells throughout the body, it allows us to think, feel, move and breathe. Neuron is an excitable cell that receives some sort of stimuli (often signal from other neurons) and responds by either sending the signal or not. In a way, a neuron is a digital circuit (either on or off) The difference is that it can fire at various rates and thus pass on processed information to other neurons.

Structure of Neuron:

Neurons have a quasi-amoeboid shape, consisting of a single long projection called an axon and shorter, typically branching projections called dendrites.

Soma:

The soma is the part of the neuron that contains the nucleus. The soma is also called cell body. The soma is the part of neuron where all the information is collected by the dendrites converge and merge. The soma, in effect calculates the sum of these informing signals (Works as Logic Gate with previous experiences) and decides whether or not to fire (more accurately, if incoming signals result in voltage that is above the certain threshold, the neuron will fire). If it triggers it sends its own signal, the neuron will then pass it on to other neurons.

Dendrites:

A branched extension of a neuron, the dendrite is a sensing or listening, part of the neuron that receives signals typically from other neurons. It conducts these signals towards the soma or the cell body. A single neuron can have as many as 2000 connections to other neurons, all coming in through its dendritic branches.

Nucleus:

Like all other cells in the body that contain nuclei the nucleus of the neuron holds the genetic code used to create protein needed by the cell.

Axon:

The axon is a filament like extension to the cell that it carries an electro-chemical signal away from the soma. From one cell type to another, the axons can vary greatly in length. (Some are very short, while others can be almost as long as person is tall). Some axons for example stretch from the base of the brain down to the tips of the toes. When neuron decides to fire, the axon’s job is to carry the signal generated at the cell body to both nearby and far away neurons to which the neuron is connected to.

Myelin Sheath:

A myelin sheath is fatty, insulating cover that surrounds portion of the axon. In addition to protecting the axon, the myelin sheath increases the speed and strength of signals transmitted down the axon. Axons that are  very long need myelin sheaths to do their jobs well, Not all neurons have myelin sheath.

Synaptic End Bulbs (Axon Terminal Buttons):

Synaptic end bulbs are the structures at the tip of the axon branches where electrical signal carried by the axon can cause the release of neurotransmitters. These neurotransmitters are received by other neurons, muscle cells and gland cells.