The central nervous systemEdit
The central nervous system (CNS) is made of the brain and the spinal cord. The CNS receives messages from receptors, and then inside the CNS, this information is processed and co-ordinated. Then, messages are sent along nerves to tell muscles or glands (effectors) what to do; these then carry out the actions.
The peripheral nervous systemEdit
This is all the rest of the nervous system, minus the CNS. Receptors send messages to the CNS along nerves, which are then processed in the CNS.