What is Nervous system?
[[File:TE-Nervous system diagram.svg|thumb|The human nervous system]] [[File:Descartes-reflex.JPG|thumb|right|Illustration of how [[pain]] travels to the brain, from [[René Descartes]]'s ''Treatise of Man'']] The '''nervous system''' is a [[body]] [[system]] which sends signals around the body. It lets animals [[wikt:react|respond]] to what is around them. The ''[[central nervous system]]'' is the [[brain]] and the [[spine|spinal cord]].<ref>{{cite web |url=http://training.seer.cancer.gov/anatomy/nervous/organization/ |title=Organization of the Nervous System |author=<!--Staff writer(s); no by-line.--> |website=Cancer.gov |publisher=National Cancer Institute |accessdate=January 20, 2016 |quote=}}</ref> It is present in almost all [[animal]]s. It is there to process the input from the [[senses]], and to coordinate [[movement]].<ref name=KandelCh17>{{Cite book| author= Kandel ER, Schwartz JH, Jessel TM| chapter=Ch. 17: The anatomical organization of the central nervous system |title = Principles of Neural Science| url= https://archive.org/details/isbn_9780838577011| year = 2000| publisher = McGraw-Hill Professional| isbn = 978-0-8385-7701-1}}</ref> [[Neuroscience]] is the scientific study of the nervous system. The nervous system is made up of [[neuron]]s. Other cells, such as [[glial cell]]s keep the neurons safe and in good condition.<ref name=Allen2009>{{Cite journal|author=Allen NJ, Barres BA |title=Neuroscience: Glia - more than just brain glue |journal=Nature |volume=457 |pages=675–7 |year=2009 |pmid=19194443 |doi=10.1038/457675a |issue=7230|bibcode=2009Natur.457..675A |s2cid=205044137 }}</ref> The structure of the system includes the brain and spinal cord, which together are called the ''central nervous system.''<ref name=KandelCh17 /> The brain has [[billion]]s of nerve cells to help think, walk, and breathe.<ref name=KandelCh2>{{Cite book| author= Kandel ER, Schwartz JH, Jessel TM| chapter=Ch. 2: Nerve cells and behavior |title = Principles of Neural Science| url= https://archive.org/details/isbn_97808