the nervous system

• Diagram of the nervous system

  
• key features of the nervous system

  • The nervous system is a specialised network of cells and our primary communication system
  • It is based on electrical (and chemical) signals
  • 2 main functions:
  • To collect, process and respond to information in the environment
  • To co-ordinate the working of different organs and cells in the body
  • Nervous system is subdivided into 2 parts:
  • central nervous system
  • Peripheral nervous system
• central nervous system (CNS)

  • CNS is made up of = the brain and the spinal cord
  • Brain:
  • Centre of conscious awareness
  • The outer layer of the brain (cerebral cortex) is highly developed in humans - what distinguishes our higher mental functions from those of animals
  • it is divided into 2 hemispheres
  • spinal cord:
  • An extension of the brain and is responsible for reflex actions
  • Passes messages to and from the brain and connects nerves to the PNS (connects brain to rest of the body)
• peripheral nervous system (PNS)

  • The PNS transmits messages (via millions of neurons) to and from the nervous system
  • PNS is subdivided into:
  • Somatic nervous system (SNS) = governs muscle movement and receives information from sensory receptors (responsible for voluntary movements)
  • Autonomic nervous system (ANS) = governs vital functions in the body (such as breathing, heart rate, digestion, stress response)
  • Functions of the ANS subdivided into = sympathetic nervous system and parasympathetic nervous system
• Sympathetic state: (fight or flight response)

  • Increased heart rate
  • Increased breathing rate
  • Dilates pupils
  • Inhibits digestion
  • Inhibits saliva production
  • Contracts rectum

  Parasympathetic state: (rest and digest response/resting)

  • decreased heart rate
  • decreased breathing rate
  • Constricts pupils
  • Stimulates digestion
  • Stimulates saliva production
  • Relaxes rectum