Seneca
Sign up

Speed of Transmission

Applied Science: BTEC Level 3 National Extended Diploma, topic 1.5.7

Transmission of Nerve Impulses

Factors that speed up the transmission of nerve impulses include:

Myelination

Myelination

  • Schwann cells wrap around the axon of neurones to create a myelin sheath.
  • The myelin sheath acts as an electrical insulator because it is impermeable to ions (Na+ and K+).
  • Depolarisation and action potentials cannot occur at the myelinated parts of the axon and can only occur in the gaps between (the nodes of Ranvier).
  • The nervous impulse jumps from one node to the next. This is called saltatory conduction.
Temperature

Temperature

  • An increase in temperature increases kinetic energy.
  • Ions move across the membrane more rapidly when they have more kinetic energy.
Axon diameter

Axon diameter

  • Giant axons are found in the giant squid and allow it to have a rapid escape response.
  • Greater axon diameter means there is a greater surface area for the movement of ions across the cell membrane.

Test yourself on Speed of Transmission

  • Which of the following are NOT a factor that speeds up transmission of nerve impulses?

Practise this topic for free