Nervous system

• Body is sensitive to changes in the world
• Receptors


  Cells that pick up changes (stimuli) in the world
• Receptor cells


  • Have a nucleus, cytoplasm and cell membrane
  • Receptors are found clustered together in sense organs
• Detecting and responding to stimuli

  1. Receptor detects stimulus

  2. Information sent as electrical impulses that pass along neurons

  3. Impulses travel along neurons until they reach the central nervous system

  4. Brain coordinates response and sends impulses along specialized cells (motor neurons)

  5. Effectors (muscles or glands) respond by contracting or secreting chemical substances
• Stimulus


  • Receptor
  • Coordinator
  • Effector
• Sensory neurons carry impulses from receptors to the central nervous system
• Motor neurons carry impulses from the central nervous system to effectors
• The central nervous system is made up of the brain and spinal cord