nervous system

• human nervous system

  • the complex network of nerve cells and fibres which transmit nerve impulses between parts of the body
  • divided into:
  • central nervous system (CNS)
  • peripheral nervous system
• division of the nervous system


  tbc
• central nervous system

  • made up of the brain and spinal cord
  • 2 main functions:
  • control of behaviours
  • regulate body's physiological processes
• spinal cord

  • relays info between the brain and the rest of the body
  • allows brain to monitor and regulate bodily functions (eg digestion and breathing) and coordinate voluntary movements
  • spinal cord is connected to different parts of the body by pain of spinal nerves
  • spinal cord also contains circuits of nerve cells that allow simple reflexes without need for the brain (eg. withdrawing your hand from something hot)
• brain divided into 4 area

  1. the cerebrum
  2. cerebellum
  3. diencephalon
  4. brain stem
• peripheral nervous system

  • nerves outside the brain and spinal cord
  • relays nerve impulses from CNS to the rest of the body + back to CNS

  2 main divisions: somatic + autonomic nervous system:
• somatic nervous system

  • 12 pairs of cranial nerves + 31 pairs of spinal nerves
  • these have sensory and motor neurons
  • sensory neurons relay messages to the CNS and motor neurons relay messages from CNS to other body areas
  • also involved in reflex actions
• autonomic nervous system

  • governs the brain's involuntary activities eg, vital bodily functions
  • control centres of the brain
  • sympathetic nervous system generally uses noradrenaline (stimulating) - ''fight or flight; neurons from SNS travel to all organs preparing for action (eg. increased heartbeat); mobilising energy)
  • parasympathetic neurons system generally uses acetylcholine (inhibiting) - relaxes once threat has passed (eg, slows heartbeat); ''rest and digest; conserving energy''