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The nous and spinal anesthesia cord ar made up of many cells, including neurons and glial cells. Neurons be cells that send and receive electro-chemical signals to and from the brain and nervous system. There are virtu every last(predicate)y 100 billion neurons in the brain. There are many to a greater extent glial cells they provide support functions for the neurons, and are far more numerous than neurons. There are many type of neurons. They vary in surface from 4 microns (. 004 mm) to 100 microns (. 1 mm) in diameter. Their length varies from a instalment of an inch to several feet.Neuronsare nervus cells that transmit nerve signals to and from the brain at up to 200 mph. The neuron consists of acell torso (or soma)with wooden legingdendrites(signal receivers) and a projection called anaxon, which conduct the nerve signal. At the former(a) end of the axon, theaxon terminalstransmit the electro-chemical signal across asynapse(the bed cover between the axon terminal and the receiving cell). The word neuron was coined by the German scientist Heinrich Wilhelm Gottfried von Waldeyer-Hartz in 1891 (he also coined the term chromosome).Theaxon, a long extension of a nerve cell, and take information away from the cell body. Bundles of axons are cognise as nerves or, within the central nervous system (central nervous system), as nerve tracts or pathways. Dendrites bring information to the cell body. Myelincoats and insulates the axon (except for half-hourly breaks called nodes of Ranvier), increasing transmission speed along the axon. Myelin is manufactured by Schwanns cells, and consists of 70-80% lipids (fat) and 20-30% protein.Thecell body (soma)contains the neurons nucleus (with DNA and typical nuclear organelles). Dendrites branch from the cell body and receive messages. 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, and so on ). DIFFERENT TYPES OF NEURONS There are antithetical types of neurons. They all hold out electro-chemical nerve signals, but differ in organize (the number of processes, or axons, emanating from the cell body) and are found in disparate parts of the body. Sensory neurons or Bipolar neuronscarry messages from the bodys sense receptors (eyes, ears, etc. ) to the CNS. These neurons have two processes. Sensory neuron account for 0. 9% of all neurons. (Examples are retinal cells, olfactory epithelium cells. ) * Motoneurons or Multipolar neuronscarry signals from the CNS to the muscles and glands. These neurons have many processes originating from the cell body. Motoneurons account for 9% of all neurons. (Examples are spinal motor neurons, pyramidal neurons, Purkinje cells. * Interneurons or Pseudopolare (Spelling) cellsform all the neural wiring within the CNS. These have two axons (instead of an axon and a dendrite). champion axon communicates with the spinal cord one with either the skin or muscle. These neurons ha ve two processes. (Examples are dorsal root ganglia cells. ) LIFE suspender OF NEURONS Unlike most other cells, neurons cannot regrow after damage (except neurons from the hippocampus). Fortunately, on that point are about 100 billion neurons in the brain. GLIAL CELLS glial cells make up 90 percent of the brains cells.Glial cells are nerve cells that dont carry nerve impulses. The various glial (meaning glue) cells perform many grand functions, including digestion of parts of dead neurons, manufacturing myelin for neurons, providing physical and nutritional support for neurons, and more. Types of glial cells include Schwanns Cells, Satellite Cells,Microglia, Oligodendroglia, and Astroglia. Neuroglia (meaning nerve glue) are the other type of brain cell. These cells guide neurons during fetal development.