The peripheral nervous system (PNS) consists of sensory neurons that pick up information from inside and outside the body and send it to the central nervous system (CNS), and motor neurons that transmit signals from the CNS to organs and tissues. The PNS has two major divisions - the somatic nervous system which controls voluntary functions like movement, and the autonomic nervous system which regulates involuntary functions like digestion. The autonomic nervous system has three divisions - the sympathetic nervous system which triggers the fight or flight response, the parasympathetic nervous system which allows relaxation, and the enteric nervous system which controls digestion.