Neurones 🧪

• What happens in the nervous system?

  1. stimulus occurs.
  2. receptor cells detect the stimulus.
  3. creates an electrical impulse.
  4. impulse sent to sensory neurone.
  5. brain processes then creates response.
  6. impulse sent to relay neurone.
  7. goes to motor neurone.
  8. Effector responds. (Gland or muscle)
• What are the three neurones?

  Sensory, relay and motor neurones.
• What is reflex action?

  It is an automatic response which protects the body from harm and has no conscious thought involved.
• What is the reflex arc?

  1. stimulus is detected by receptor cells.
  2. sensory neurone sends electrical impulses to the relay neurone.
  3. no brain involved.
  4. relay neurone to motor neurone which carried to effectors.
• What is the function of the sensory neurone?

  To carry impulses from receptor cells to the central nervous system.
• What are the adaptations of the sensory neurone?

  -long dendrons to allow faster transmission.

  -many dendrites to allow neurone to receive impulses.

  -many axon terminals to allow impulse to be passed to next neurone.

  -Myelin sheath, a fatty layer that surrounds axon and speeds up neuro transmission, insulates impulse so it isn't lost.
• Draw and label a diagram of a sensory neurone.


  This is the diagram:

  
• What is the function of the relay neurone?

  It is found in the spinal cord where they link the sensory neurone to the motor neurone.
• What are the adaptations of the relay neurone?

  -No dendron

  -Dendrites on cell body

  -No myelin sheath

  -only connects other two neurones so no need for sheath as it travels fast.
• Draw and label diagram of a relay neurone.


  This is the diagram:

  
• What is the function of the motor neurone?


  It carries responses to effectors e.g. muscles or glands.
• What are the adaptations of the motor neurone?

  -many dendrites

  -long axon

  -myelin sheath

  many axon terminals
• Draw and label a diagram of a motor neurone.


  This is the diagram:

  
• What is a synapse?

  It is the tiny gap between neurones when one meets another.
• What is synapse transmission?

  1. Electrical impulse travels from dendrites to axon terminals.
  2. impulse reaches end of neurone and changes into a chemical signal.
  3. known as neurotransmission and synapse triggers release of neurotransmitters.
  4. diffuse across synapse.
  5. neurotransmitters bind to receptors on next neurone.
  6. triggers a new electrical impulse generated in next neurone.
• What do painkillers do to synapse transmission?

  • prevent neurotransmitters from binding to receptors.
  • pain killers bind to receptors instead.
  • prevents electrical impulse from being triggered.
  • signal is not received by CNS.
  • brain cannot process pain so no pain felt.
• Draw and label a diagram of a synapse.


  This is the diagram: