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The Amazing Neuron by Gary Trotta |
 There are few things more amazing in our world than the Neuron. We have around 100 billion of these wondrous little cells in our brain, each having thousands of connections to one another and total approximately 100 trillion connections in all. We don't see with our eyes, hear with our ears or taste with our tongue. We do all these things with our brain and the structural and functional unit of the brain is the Neuron.
The neuron uses electrical and chemical processes to communicate. In a simple sense there are three basic parts of the neuron: the cell body, its dendrites (branches) and its axon extending from the cell body. With the cell body in the center, communications are received by the dendrites and passed along through the axon. To explain I'll start at the top of the axon called the axon hillock. It is a kind of electrical gate. Cells have ions or atoms with electrical charge (+/- electrons), and the neuron is maintained or is at rest at a negative 70 millivolts. It takes a lot of energy just to keep your brain in this restful state (our brains use around 20% of our total energy, which is a lot for a little 3 pound body part). Electrical charge builds up in the cell (either negative or positive) until it reaches a particular level and then it fires. The axon hillock in an all or none fashion sends current soaring down the cell to the pre-synaptic terminal. The charge, when it reaches the pre-synaptic terminal, causes calcium ions to enter the terminal which result in little vesicles releasing neurotransmitters. These neurotransmitters (the chemical part in all this) work their way to the cell's membrane, then out into the synaptic cleft (extra cellular space between two neurons). They then sail over to one of the thousand receiving dendritic spines of a neighboring neuron. Here little receptors on the dendrite's membrane interact with the neurotransmitter, resulting in more charged ions entering the dendrite at the post synaptic terminal of this next neuron. Thus the electrical charge of this next neuron begins to change either positively or negatively. If negatively, the cell is becoming depolarized or excited; if positively, hyperpolarized or inhibited. The total effect of all the cells dendrictic stimulation changes the cell charge either negatively or positively and eventually causing it to fire again or not. At any rate this is how our neurons allow us to think and see, and hear and taste and feel and if that isn't amazing, nothing is. |
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