Here we see one NEURON (total population 12-15 billion) discharging an ACTION POTENTIAL (red) down its AXON (the long smooth black filament).
The DENDRITES (the short, crooked filaments) receive INHIBITORY (yellow) or EXCITATORY (green) input, day and night, from other AXONS from all over the place. The SYNAPSE is the point of contact (up to 10K per neuron) where electric signals are turned into chemical signals and once on the other side, back into electric signals.
Inhibition predominates in the CNS (Central Nervous System.) The excitable neuron is continuously being calmed down like a Red Setter on a ski-lift getting a back tickle. Or Uranium rods in a nuclear core kept under control by graphite or water.
From time to time, excitation overwhelms inhibition and the ACTION POTENTIAL, a wave of intra/extracelluar polarity reversal, ploughs down the Axon at 50-60 miles an hour in humans (slow by today's standards, but still the fastest in the biologic realm) hits the cell wall at the tip (up to 3 feet for certain spinal motor neurons) and blasts loose VESICLES full of NEUROTRANSMITTERS, most commonly ACETYLCHOLINE (AcH), into the synaptic cleft. At least 25 neurotransmitters have been identified although only one per neuron is mission critical. Entire functional systems such as the sympathetic and parasympathetic autonomic systems are consistent and coherent in their neurotransmitters.
Meanwhile, overseeing the action are the GLIA (glue cells) or ASTRO (star)CYTES, (small round black cells) which appear to do a little bit of everything. Now they're repairing MYELIN (axonal insulation), soaking up potassium ions, transforming into MACROPHAGES and scarphing up debris. The microglia perform immune functions and are suspect in MS, SLE and other auto-immune diseases. Even Alzheimer's and ALS have recently been hypothesized to have an auto-immune basis.
But just how all these excited neurons result in YOU and ME hasn't been fully explained.
Nor is an "explanation" to be expected:
"The word 'mind' names one of our most important, but most confused and confusing, ideas......I dare say there is something bizarre about the materialist-reductionist's denial of persons. To be sure, brains in craniums exist..."
from The Meaning of Mind by Thomas Szasz, Praeger Press, 1996.
The widespread notion that neuro-science is on the verge of "explaining" human consciousness is profitable and priestly propaganda.
By the way, there is a grievous ERROR in my animation above. Can you find it? *
Return to the Library. or
*
(to read: hold computer up to mirror or vice versa)