Editing Nervous system (section)

====Glial cells====
[[Glial cell]]s (named from the Greek for "glue") are non-neuronal cells that provide support and [[nutrition]], maintain [[homeostasis]], form [[myelin]], and participate in signal transmission in the nervous system.<ref name=Allen2009/> In the [[human brain]], it is estimated that the total number of glia roughly equals the number of neurons, although the proportions vary in different brain areas.<ref name=Azevedo/> 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 [[pathogen]]s and remove dead neurons; and to provide guidance cues directing the axons of neurons to their targets.<ref name=Allen2009/> A very important type of glial cell ([[oligodendrocyte]]s in the central nervous system, and [[Schwann cell]]s 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. Recent findings indicate that glial cells, such as microglia and astrocytes, serve as important resident immune cells within the central nervous system.