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Glossary
  1. diffuse When particles spread out from a region of higher concentration to a region of lower concentration.
  2. effector Organ which has an effect when stimulated (eg muscles or glands).
  3. hormone Chemical messengers produced in glands and carried by the blood to specific organs in the body.
  4. motor neurone The nerve cell that carries electrical impulses from the CNS to effectors such as muscles or glands.
  5. neurone Another term for a nerve cell that is specialised to transmit electrical impulses.
  6. neurotransmitter Chemical involved in passing nerve impulses from one nerve cell to the next across a synapse.
  7. reflex action Automatic and rapid response to a stimulus.
  8. relay neurone The nerve cell that transmits electrical impulses from sensory neurones to motor neurones.
  9. sensory neurone The nerve cell that transmits electrical impulses from receptors in the sense organs to the CNS.
  10. stimuli Things that set off a reaction in the nervous system, for example, light, heat, sound, gravity, smell, taste, or temperature. The singular is stimulus.
  11. stimulus Any change in the environment that can be detected by receptors in an organism.