Synapses in human brain

Diagram of a neuronNEURONS & SYNAPSES

The core component of the nervous system in general, and the brain in particular, is the neuron or nerve cell, the brain cells of popular language. A neuron is an electrically excitable cell that processes and transmits information by electro-chemical signalling. Unlike other cells, neurons never divide, and neither do they die off to be replaced by new ones. By the same token, they usually cannot be replaced after being lost, although there are a few exceptions.

The average human brain has about 100 billion neurons (or nerve cells) and many more neuroglia (or glial cells) which serve to support and protect the neurons (although see the end of this page for more information on glial cells). Each neuron may be connected to up to 10, 000 other neurons, passing signals to each other via as many as 1, 000 trillion synaptic connections, equivalent by some estimates to a computer with a 1 trillion bit per second processor. Estimates of the human brains memory capacity vary wildly from 1 to 1, 000 terabytes (for comparison, the 19 million volumes in the US Library of Congress represents about 10 terabytes of data).


Diagram of a neuron
Picture from Wikipedia (

Unlike other body cells, most neurons in the human brain are only able to divide to make new cells (a process called neurogenesis) during fetal development and for a few months after birth.
These brain cells may increase in size until the age of about eighteen years, but they are essentially designed to last a lifetime.
Interestingly, the only area of the brain where neurogenesis has been shown to continue throughout life is the hippocampus, an area essential to memory encoding and storage.
Information transmission within the brain, such as takes place during the processes of memory encoding and retrieval, is achieved using a combination of chemicals and electricity. It is a very complex process involving a variety of interrelated steps, but a quick overview can be given here.

A typical neuron possesses a soma (the bulbous cell body which contains the cell nucleus), dendrites (long, feathery filaments attached to the cell body in a complex branching dendritic tree) and a single axon (a special, extra-long, branched cellular filament, which may be thousands of times the length of the soma).

Every neuron maintains a voltage gradient across its membrane, due to metabolically-driven differences in ions of sodium, potassium, chloride and calcium within the cell, each of which has a different charge. If the voltage changes significantly, an electrochemical pulse called an action potential (or nerve impulse) is generated. This electrical activity can be measured and displayed as a wave form called brain wave or brain rhythm.


Synaptic transmission
Picture from Wikipedia (

This pulse travels rapidly along the cell's axon, and is transferred across a specialized connection known as a synapse to a neighbouring neuron, which receives it through its feathery dendrites. A synapse is a complex membrane junction or gap (the actual gap, also known as the synaptic cleft, is of the order of 20 nanometres, or 20 millionths of a millimetre) used to transmit signals between cells, and this transfer is therefore known as a synaptic connection. Although axon-dendrite synaptic connections are the norm, other variations (e.g. dendrite-dendrite, axon-axon, dendrite-axon) are also possible. A typical neuron fires 5 - 50 times every second.

You might also like

Scientists One Step Closer to a Bionic Brain (VIDEO)
Scientists One Step Closer to a Bionic Brain (VIDEO)
New imaging technology called CLARITY allows scientists to
New imaging technology called CLARITY allows scientists to ...
Scientists Build Simple Artificial Brain - TYT Science
Scientists Build Simple Artificial Brain - TYT Science
Scientists One Step Closer to a Bionic Brain
Scientists One Step Closer to a Bionic Brain
EISCO Eisco Labs Human Model of Functional Brain - 1/2 Size
BISS (EISCO)
  • Color coded to show areas of brain function.
  • One half of the size of a actual brain
  • Comes with Stand and rod to display
  • Comes with ID key card
3D human brain map points way to future discovery
3D human brain map points way to future discovery
Scientists Build Tiny Human Brains in the Lab
Scientists Build Tiny Human Brains in the Lab

Q&A

avatar
How does lack of stimulation, psychological deficits or inability to satiate certain needs affect the anatomy of the human brain?

2. Desire Bacon
3. Love Bacon
4. Scheme to rob a bank in order to purchase Bacon
5. Provide motivation to work for Bacon
6. Clone pigs to make Bacon
7. And it is chopped up and put into Scrapple when you die.

avatar
In psychology, what are the 7 functions of the Human Brain? | Yahoo Answers

1. Eat Bacon
2. Desire Bacon
3. Love Bacon
4. Scheme to rob a bank in order to purchase Bacon
5. Provide motivation to work for Bacon
6. Clone pigs to make Bacon
7. And it is chopped up and put into Scrapple when you die.

Copyright © . All Rights Reserved