The divisions of the nervous system

• The nervous system is a specialised network of cells in the human body and is our primary internal communication system. It has 2 main functions -

  1. collect, process and respond to information from the environment
  2. co-ordinate organs and cells internally
• CNS = brain + spinal chord. This system is responsible for life functions and conscious psychological processes.

  The brain is responsible for conscious awareness, perception and sleep.

  The spinal cord connects the brain to the rest of the body and with the external world. Also some unconscious movements e.g. reflexes.
• Peripheral NS (PNS) transmits information between CNS and external world/organs. 2 further divisions -

  1. Somatic NS = responsible for voluntary movement e.g. walking. Transmits info between CNS and the senses. Carries sensory info from the environment to the brain and provides muscle responses via motor pathways.
  2. Autonomic NS = Involuntary bodily activities e.g. homeostasis, heartrate etc. and not under conscious control.
• Autonomic NS has two further sub-divisions -

  1. Sympathetic NS = increases bodily activity to prepare for action e.g. fight or flight response. Less important functions are suppressed e.g. digestion.
  2. Parasympathetic NS = returns the body to 'normal' functioning and will decrease all the actions taken by the Sympathetic NS.
• Differences between the autonomic ns and the somatic ns?

  • the autonomic ns is involuntary whereas the somatic ns is under conscious control
  • ANS controls smooth muscles and glands whereas SNS controls skeletal muscles
  • the autonomic ns has two further sub-divisions whereas the somatic ns doesn't