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The wag and spinal cord be made up of some an separate(prenominal) cellular phones, including neurons and glial cells. Neurons argon cells that send and cod electro-chemical signals to and from the brain and nervous system. in that location be roughly 100 cardinal neurons in the brain. There be many more glial cells they provide support functions for the neurons, and are uttermost more numerous than neurons. There are many attribute of neurons. They vary in size from 4 microns (. 004 mm) to 100 microns (. 1 mm) in diameter. Their length varies from a split of an inch to several feet.Neuronsare punk cells that channelize brass signals to and from the brain at up to 200 mph. The neuron consists of acell automobile trunk (or soma)with branchingdendrites(signal receivers) and a projection c solelyed an axone, which conduct the aspect signal. At the other end of the axon, theaxon terminalstransmit the electro-chemical signal across asynapse(the breakage between the a xon terminal and the receiving cell). The condition neuron was coined by the German scientist Heinrich Wilhelm Gottfried von Waldeyer-Hartz in 1891 (he also coined the term chromosome).Theaxon, a extensive extension of a nerve cell, and scoop up information away from the cell body. Bundles of axons are known as nerves or, inside the CNS (central nervous system), as nerve tracts or pathways. Dendrites bring information to the cell body. bulbcoats and insulates the axon (except for periodic breaks c everyed nodes of Ranvier), increase 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 atomic organelles). Dendrites branch from the cell body and receive messages. A typical neuron has to the highest degree 1,000 to 10,000 synapses (that is, it communicates with 1,000-10,000 other neurons, muscle cells, glands, etc. ). divers(preno minal) TYPES OF NEURONS There are discordent types of neurons. They all carry electro-chemical nerve signals, but differ in structure (the number of processes, or axons, emanating from the cell body) and are found in different parts of the body. Sensory neurons or Bipolar neuronscarry messages from the bodys sense receptors (eyes, ears, etc. ) to the CNS. These neurons have 2 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 spooky wiring within the CNS. These have twain axons (instead of an axon and a dendrite). One axon communicates with the spinal cord one with either the skin or mus cle. These neurons have two processes. (Examples are dorsal root ganglia cells. ) animateness SPAN OF NEURONS Unlike most other cells, neurons cannot regrow after damage (except neurons from the hippocampus). Fortunately, in that respect are about 100 billion neurons in the brain. GLIAL CELLS Glial cells arouse up 90 percent of the brains cells.Glial cells are nerve cells that dont carry nerve impulses. The unhomogeneous glial (meaning glue) cells perform many important 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 another type of brain cell. These cells guide neurons during fetal development.