How a Response is Generated by Effectors (Edexcel International A Level Biology)

• The nervous system enables the body to detect changes in the environment and brings about appropriate responses to ensure its safety
  
  • Receptor cells detect changes in the environment, or stimuli
  • Nerve impulses travel from the receptor cells along sensory neurones to the central nervous system, or CNS
  • The CNS acts as a coordinating centre for the impulses that arrive from the receptors, determining which part of the body needs to respond and sending out a new set of impulses along motor neurones
  • Motor neurones send impulses to the effectors to bring about a response
    • Effectors may be muscles or glands
• Nerve impulses pass through the nervous system along the following pathway

stimulus  receptor  sensory neurone  CNS motor neurone effector

Receptors detect stimuli and impulses are sent through to the nervous system to bring about a response in the effector