An Overview of Human Cells for Light Microscopists
A 3D modelling article
by Mol Smith 2010
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  Generic Human Cell  Neurons  Synapses    Resources and external links
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Information Processing - The Synapses
My movie below (made from using virtual 3D models) clearly shows how one Neuron communicates with another. An electrical signal travels along the Axon or Dendron to the Dendrites where chemical messaging molecules 'swim' across the synaptic gap to appropriate receiving pores on the other cell. The reception of the transmitter chemical triggers an electrical signal in the interconnecting cell. Some forms of mental ill health - notably, depressive illnesses - are thought to be caused by an imbalance or reduced quantity of one or more chemical transmitters (e.g. dopamine, serotonin).







Neurons also exist throughout the human body and transmit signals to and from the brain at up to 200 mph. The axon is a long extension of a nerve cell, and takes information away from the cell body {A&D}. Bundles of these axons are what we commonly term 'nerves' when located away from the brain (Central Nervous System - CNS). Dendrites bring information to the cell body
{
B & C}. The Axon is insulated (like a copper stranded wire is with plastic) by a Myelin coating, except for periodic breaks called nodes of Ranvier, increasing transmission speed along the Axon. The Myelin is manufactured by Schwann's cells, and consists of 70-80% lipids (fat) and 20-30% protein. The cell body (soma) contains the neuron's nucleus (with DNA and typical nuclear organelles).

A typical neuron has about 1,000 to 10,000 synapses (that is, it communicates with 1,000-10,000 other neurons, muscle cells, glands, etc.). The complexity of such a network confounds our attempts to fully comprehend the staggering complexity and sheer sophistication of the human brain.

This exquisite schematic diagram below (
Public Domain from Wiki) reiterates the process very clearly.

A public domain image from Wiki please see
http://en.wikipedia.org/wiki/File:Chemical_synapse_schema_cropped.jpg
for reuse permissions


Before leaving our brief look at the Neuron, I would like to inspire you with another image and some personal observations - not so scientific, but interesting theoretically none-the-less. Here is a conceptualised network of neurons in the human brain. We may well think of the brain (mind) a bit like a Turin Machine (computer), where information comes in through a variety of physical senses, is mapped and compared with previous information, and then used to activate an external response (run, shout,) or make a decision, or even just determine another perspective about our external world. Nothing comes out which isn't already 'put-in' in the first place. But this idea may not be entirely true! Roger Penrose, a distinguished UK mathematician and associate of Stephen Hawking, believes micro (nano) organelles may exist in the brain which allow information in a general sense to enter the system from the quantum world of sub-atomic particles and energy packets. This was put forward in one of his book's -
The Emperor's New Mind and I would recommend reading this work if you believe the mind/brain is no more than a very sophisticated computer.

Next month, I will continue this series by looking at other cells with the aid of 3D virtual modelling.
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Published in April 2010 Micscape Magazine.
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