The major components of the nervous system and their functional relationships. (A) The CNS (brain and spinal cord) and PNS (spinal nd cranial nerves). (B) Diagram of the major components of the central and peripheral nervous systems and their functional relationships. Stimuli from the environment convey information to processing circuits within the brain and spinal cord, which in turn interpret their significance and send signals to peripheral effectors that move the body and adjust the workings of its internal organs. (reproduced from Neuroscience. Fourth Edition. Fig. 1.10 provided by Dr. Purves).