3“Movement” of an action potential Once an action potential has been created it passes down the axonThe initial action potential and depolarisation of the membrane stimulates an action potential in the next region of the axonReversal of charge across the membrane is reproduced along the axon
4Passage of an action potential along an unmyelinated axon Resting potential:High Na+ concentration outsideHigh K+ concentration insideInside negative relative to outsideAxon membrane polarised
5Passage of an action potential along an unmyelinated axon Stimulus receivedInflux of sodium ionsMembrane depolarised – action potential started
6Passage of an action potential along an unmyelinated axon Localised electrical circuits formInflux of sodium causes opening of sodium voltage-gated channels further along
7Passage of an action potential along an unmyelinated axon Action potential propagated along the neurone.Areas that have become depolarised become repolarised due to movement of K+ outside of the membraneSodium-potassium pump starts back up returning membrane to resting potential
8Passage of an action potential along a myelinated axon Fatty sheath of myelin around axons act as insulator preventing action potentials forming.Breaks in sheath (called nodes of Ranvier) at intervals of 1-3mmAction potentials occur at these points and jump from node to node. This process is called saltatory conduction. This speeds up the passage of the action potential.