NERVE CELLS – THE BRAIN’S WORKFORCE
THE FUNDAMENTAL units of the brain, too small to see in Willis’s time, are two types of nerve cells. One type, the neuroglia (or glial-“glue”- cells), has the rather pedestrian task of supporting the nervous system. Neuroglia play a role in guiding neurons toward making connec- tions, promoting neuron health, insulating neuronal processes, and otherwise influencing neuronal functioning and, thus, information processing in the brain. Glial cells continue to divide over the course of a lifetime and fill in spaces in the brain. Glial cells come ill SiX varieties, with some playing a key role in physical health by attacking invading microbes.
The human brain has about 100 billion neurons and about 50 trillion neuroglia.
The other type of cell in the brain is the nerve cell, or neuron. In the late 1800s, a Spanish neuroscientist, Santiago Ramon y Cajal, used a special solution containing silver to stain nerve cells and examine them under a microscope in great detail. Ramon y Cajal’s method worked on only about one in a hundred cells. Nevertheless, he was able to observe enough of the sil- ver-encrusted neurons to describe them in vivid detail. The nerve cell was the “aristocrat among the structures of the body,” he said, “with its giant arms stretched out like the tentacles of an octopus to the provinces on the frontier of the outside world, to watch for the constant struggles of physical and chemical forces.”
Seen en masse in the outer regions of the human brain, neurons appear gray to the naked eye. Hence, scientists exploring the brain described neurons as gray matter. When Agatha Christie’s fictional detective Hercule Poirot brags of the detec- tive work of his “little gray cells,” he is praising his neurons.
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