6.2.5 Speed of Nerve Impulses

• Factors affecting speed of action potential:

  • Mylein Sheath
  • Diameter of axon
  • Temperature
• Axon diameter – The greater the diameter of the axon the faster the impulse travels.
• Temperature – The higher the temperature, the faster the speed of the impulse. Temperature affects the rate of diffusion of ions across the axon.
• Myelination – The greater the myelination of the axon the faster the impulse travels.
• The action potential moves from node to node. This is referred to as saltatory conduction and is much quicker than the step-by-step conduction that occurs in a non-myelinated neurone.