It might be helpful to think of these two parts of the nervous system as on - and - off switches. (psychologyofeating.com)
This is one of the most essential requirements for the proper functioning of your nervous system and it also helps in maintaining the healthy blood cells. (momdiscuss.com)
There is a scale of intrinsic value which presumably bears some relation to the development of the nervous system of the organism. (religion-online.org)