1. The nervous system

• Nervous system


  Specialised network of cells in our body that works as an internal communication system
• Main functions of the nervous system

  • To collect process and respond to information in our environment
  • To co-ordinate the working of different organs within our body
• Sub-systems of the nervous system

  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)
• Central nervous system (CNS)


  • The origin of all complex demands and decisions
• Components of the CNS

  • The brain - the centre of all conscious awareness
  • The spinal cord - Extension of the brain and responsible for reflex actions
• Peripheral nervous system (PNS)


  • Sends information from the to and from the CNS, through millions of neurones
• Subdivisions of the PNS

  • Somatic nervous system (SNS)
  • Autonomic nervous system (ANS)
• Somatic nervous system (SNS)


  • Controls muscle movement and receives information from sensory receptors
  • Transmits information from receptor cells to CNS
  • Receives information from the CNS then directs the muscle to act
• Autonomic nervous system (ANS)


  • Governs vital functions of the body -breathing, heart rate, sexual arousal, digestion and stress response
  • Operates automatically
  • Transmits information to and from internal body organs to govern functions
• Divisions of the ANS


  • Sympathetic division - fight or flight
  • Parasympathetic division - rest and digest
• Sympathetic division


  • Keeps us on alert
  • Prepares the body for fight or flight
  • Increases our heart rate and breathing rate, and reduces our blood pressure.
• Parasympathetic division

  • Relaxes our body
  • Responsible for returning it back to its normal resting state
  • Slows down our heart rate and breathing rate, and reduces our blood pressure.