5.3.4

• Local currents

  opening of Na+ channels at one particular point in the neurone upsets the balance of Na/K ions set by Na/K pump

  • when Na+ are allowed to flood into neurone causing depolarisation, creating local currents in the cytoplasm of the neurone

  → Na+ ions begin to move along neurone towards regions where concentration is still lower

  → the local currents cause a slight depolarisation of membrane + cause Na+ further along the membrane to open (positive feedback)