nervous system

• nervous system


  central nervous system (CNS)

  • spinal cord
  • brain

  peripheral nervous system (PNS)

  • autonomic nervous system $\mapsto$ sympathetic nervous system $\mapsto$parasympathetic nervous system
  • somatic nervous system
• cns


  • passes messages to and from the brain
  • connects nerves to pns
• brain


  • centre of all conscious awareness
  • cerebral cortex - outer layer, highly developed in humans
  • divided into two hemispheres
• nervous system

  
• spinal chord


  extension of the brain - responsible for reflex actions
• pns


  divided into two parts:

  • somatic nervous system (sns)
  • autonomic nervous system (ans)
• ans


  • controls involuntary muscles
  • vital organs such as heart rate, breathing rate and digestion etc

  unconscious motor
• sns


  • controls voluntary muscles
  • receives information from sensory receptors

  conscious motor
• ans - unconscious motor

  sns - conscious motor
• acute stress - short term

  chronic stress - long term
• somatic - body
• ans is involuntary
• sympathetic pathway


  activated during high arousal
• parasympathetic pathway


  activated during relaxation
• ans


  divided into two parts:

  • sympathetic nervous system
  • parasympathetic nervous system
• ans


  parasympathetic and sympathetic pathways act antagonistically (opposites)
• anxiety and fear


  important for survival, act as mechanism to protect body against stress and danger
• sympathetic nervous system


  controls 'fight or flight'
• sympathetic adrenal medullary axis (sam)


  sam

  
• sympathetic adrenal medullary axis


  1. hypothalamus receives sensory information
  2. activates the ans- sympathetic nervous system branch
  3. causes the adrenal medulla to release adrenaline and nor - adrenaline
• sympathetic - arouses

  parasympathetic - returns to normal (opposite)
• effect of ans (sympathetic) - heightened senses

  • pupils dilate - to allow more information
  • ears - more sensitive hearing
  • mouth - salivary glands inhibit fluid production (dry mouth)
  • face - pale (blood goes to muscles)
  • heart - increased heart rate, to increase blood flow and pump oxygen around body to muscles (so they can respire)
  • lungs - increased breathing rate, allow more oxygen into body
  • goosebumps
  • digestive system - non emergency bodily processes are suppressed (shut down), to save energy
  • sweat
  • bladder - relaxes
  • endorphins - blocks pain
• effect of ans (parasympathetic) - relaxes senses

  • pupils constrict - to allow less information
  • ears - less sensitive hearing
  • mouth - salivary glands produce fluid
  • face - red (blood returns to face)
  • heart - slowed heart rate, to decrease blood flow
  • lungs - decreases breathing rate
  • digestive system - working again
  • bladder - contracts
  • pain- no endorphins
• nervous system


  uses neurones