Nervous System + Responding to Stimuli

• Receptors


  Receptors detect stimuli. Receptors in the sense organs (eyes, ears, nose etc) are groups of cells that detect external stimuli.
• Effectors


  Effectors are cells that bring about a response to stimuli. They include muscle cells and cells found in glands. Effectors respons in different ways - muscle cells contract, whereas glands screte hormones
• Receptors ... with effectors via the ... or the ...


  receptors communicate with effectors via the nervous system or the hormonal system or sometimes both.
• What is the nervous system made up of 


  • all the neurons (nerve cells) in your body.
• What are the three main types of neurone?

  • sensory neurone
  • relay neurone
  • motor nerurone
• What does the central nervous system (CNS) consist of? 


  • the brain
  • the spinal cord
• What do receptors in a sense organ do when they detect a stimuli?


  they send electrical impulses along sensory neurones to the CNS
• What does the CNS do when it recieves electrical impulses?

  It sends electrical impulses to an effector along a motor neuron. The effector responds accordingly.
• What is the job of the CNS?


  to coordinate the response.
• what do coordianted responses need?

  • a stimulus
  • a receptor
  • an effector
• how do neurons transmit information? how does this help the nervous system? 


  they use high speed electrical impulses

  therefore the nervous system is able to bring about very rapid responses.
• What are Synapses?


  the connection between two neurones
• How are nerve signals transported over synapes?


  the nerve signal is transfered by chemicals called neuro transmitters which diffuse across the gap.

  these chemicals then set off a new electrical signla in the next neurone.