Changes

The nervous system is present in some form in all chordates with the the simplest system represented in the [[flatworms]], which has two nerve cords running on opposite sides that connect to two simple [[brain|brains]] called [[ganglia]].  

The nervous system is present in some form in all chordates with the the simplest system represented in the [[flatworms]], which has two nerve cords running on opposite sides that connect to two simple [[brain|brains]] called [[ganglia]].  

In the more complex [[vertebrates]] the nervous system is divided into two parts with the [[peripheral nervous system]] being defined as nervous tissue on the periphery of the body, basically everything other than the [[spinal cord]] and brain which are defined as part of the [[central nervous system]].  

In the more complex [[vertebrates]] the nervous system is divided into two parts: the [[central nervous system]], composed of the [[brain]] and the [[spinal cord]]; and the [[peripheral nervous system]], which is composed of all the nervous tissue throughout the rest of the body.  

==References==

==References==

*Martin, JH (2003). Neuroanatomy text and atlas 3rd ed., New York: McGraw-Hill.  

*Martin, JH (2003). Neuroanatomy text and atlas 3rd ed., New York: McGraw-Hill.  

* Sanes, Reh, Harris (2005). Development of the Nervous System, 2nd edition. Academic Press; ISBN 0-12-618621-9

*Sanes, Reh, Harris (2005). Development of the Nervous System, 2nd edition. Academic Press; ISBN 0-12-618621-9

 

[[Category:Biology]]

[[Category:Biology]]