Neurones

• Receptor --> Sensory neurone --> Relay neurone (to the brain) --> Motor neurone --> Effector
• The job of these neurons is to carry impulses really fast.
• Neurones are specialised cells. How are they adapted?

  • Long
  • Have an insulating layer called the myelin sheath
  • Have branched endings
• Motor neurone:

  A) branch nerve endings

  B) Muscle

  C) direction of impulse -->

  D) Axon

  E) Myelin sheath

  F) Cell body

  G) Dendrite

  H) Nucleus
• The motor neurone carry electrical impulses from the CNS to a muscle and the nerve endings are found on the effector (muscle).
• Sensory neurone:

  A) Skin

  B) Receptor cell

  C) Myelin sheath

  D) Axon

  E) Cell body

  F) Nucleus

  G) impulse towards CNS

  H) Branched nerve endings

  
• Sensory neurones carry electrical impulses from the sense organs to the brain (CNS)
• Relay neurone

  A) Dendrite

  B) Cell body

  C) Axon

  D) Synaptic endings

  
• Relay neurones are important parts of the reflex actions. They are short neurones and are only found in the CNS. They connect sensory neurones to motor neurones.
• The myelin sheath is made up of schwann cells. It increases the speed of transmission of an electrical impulse. Multiple sclerosis is the medical condition where the myelin sheath degenerates.
• Neurones:

  A) sensory

  B) relay

  C) motor