the nervous system

• central nervous system (CNS)


  -brain: centre of conscious awareness; 2 hemispheres; control centre for all functions

  -spinal chord: extension of the brain, responsible for reflex actions, passes messages to & from the brain, connects nerves to the PNS

  -origin of all complex demands & decisions
• peripheral nervous system (PNS)

  -sends info to CNS from the outside world & transmits messages from the CNS to muscles & glands

  -consists of the SNS and the ANS

  -transmits messages via millions of neurones to & from the CNS
• somatic nervous system (SNS)


  -transmits info from receptor cells in sense organs to the CNS

  -receives info from the CNS that directs muscles to act
• autonomic nervous system (ANS)


  -transmits info to & from internal organs

  -operates involuntarily & has 2 divisions: sympathetic & parasympathetic

  -sympathetic: active, alert, automatic functions, plays a role in homeostasis (maintaining internal processes)

  -parasympathetic: rest & digest
• 2 functions of the nervous system

  -collect, process & respond to info in the environment

  -co-ordinate the working of different organs & cells in the body