nervous system

• nervous system

  = specialised network of cells in the human body and is our primary internal communication system.

  • based on electrical and chemical signals.
  • to collect, process and respond to information in the environment.
  • to co-ordinate the working of different organs and cells in the body.
• central nervous system

  = made up of the brain and spinal cord.

  • the brain is the centre of all conscious awareness. Brains outer layer, cerebral cortex, only 3mm thick.
  • brain is highly developed in humans and is what distinguishes our higher mental functions from those of other animals.
  • brain is divided into 2 hemispheres.
  • spinal cord is an extension of the brain, it passes messages to and from the brain and connects nerves to the PNS. Responsible for reflex actions.
• peripheral nervous system

  = transmits message, via millions of neurons to and from the central nervous system:

  • autonomous nervous system= transmits information to and from internal bodily organs, systems operates involuntarily. It has two main divisions: sympathetic and parasympathetic
  • somatic nervous system= transmits information from receptor cells in the sense organ to the CNS. It also retrieves information from the CNS that directs muscle to act.