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Grey matter (which is only grey in preserved tissue, and is better described as pink or light brown in living tissue) contains a high proportion of cell bodies of neurons.

White matter is composed mainly of myelinated axons, and takes its color from the myelin.

The nervous system derives its name from nerves, which are cylindrical bundles of fibers (the axons of neurons), that emanate from the brain and spinal cord, and branch repeatedly to innervate every part of the body.

Nerves are large enough to have been recognized by the ancient Egyptians, Greeks, and Romans, but their internal structure was not understood until it became possible to examine them using a microscope.

Both autonomic and enteric nervous systems function involuntarily.

Nerves that exit from the cranium are called cranial nerves while those exiting from the spinal cord are called spinal nerves.

It was in the decade of 1960 that we became aware of how basic neuronal networks code stimuli and thus basic concepts are possible (David H. The molecular revolution swept across US universities in the decade of 1980.

It was in the decade of 1990 that molecular mechanisms of behavioral phenomena became widely known (Eric Richard Kandel)." A microscopic examination shows that nerves consist primarily of axons, along with different membranes that wrap around them and segregate them into fascicles.

The PNS is divided into a) somatic and b) autonomic nervous system, and c) the enteric nervous system. The autonomic nervous system is further subdivided into the sympathetic and the parasympathetic nervous systems."It is difficult to believe that until approximately year 1900 it was not known that neurons are the basic units of the brain (Santiago Ram? Equally surprising is the fact that the concept of chemical transmission in the brain was not known until around 1930 (Henry Hallett Dale) and (Otto Loewi).We began to understand the basic electrical phenomenon that neurons use in order to communicate among themselves, the action potential, in the decade of 1950 (Alan Lloyd Hodgkin, Andrew Huxley and John Eccles).Among the most important functions of glial cells are to support neurons and hold them in place; to supply nutrients to neurons; to insulate neurons electrically; to destroy pathogens and remove dead neurons; and to provide guidance cues directing the axons of neurons to their targets.A very important type of glial cell (oligodendrocytes in the central nervous system, and Schwann cells in the peripheral nervous system) generates layers of a fatty substance called myelin that wraps around axons and provides electrical insulation which allows them to transmit action potentials much more rapidly and efficiently.

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