the nervous system

• Nervous system

  A specialised network of cells in the human body and is our primary internal communication system. It is based on electrical and chemical signals whereas the endocrine system is based on hormones
• Nervous system

  • Collects, processes and responds to information in the environment
  • Co-ordinates the working of different organs and cells in the body
• Subsystems of the nervous system

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


  Made up of the brain and the spinal cord. The brain is the centre of all conscious awareness. The brain's outer layer, the cerebral cortex, is only 3 mm thick and covers the brain. It is only found in mammals.
• The brain is highly developed in humans and is what distinguishes our higher mental functions from those of other animals. Only a few living creatures-sponges, sea squints, jellyfish-do not have a brain.
• Spinal cord


  An extension of the brain. It passes messages to and from the brain and connects nerves to the PNS. It is also responsible for reflex actions such as pulling your hand away from a hot plate.
• Peripheral nervous system (PNS)

  Transmits messages, via millions of neurons (nerve cells), to and from the central nervous system
• Subdivisions of the PNS

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


  Governs vital functions in the body such as breathing, heart rate, digestion, sexual arousal and stress responses
• Somatic nervous system (SNS)


  Governs muscle movement and receives information from sensory receptors