Nerve fibre node Coloured transmission electron micrograph TEM of a crosssection through a nerve fibre axon at a node of Ranvier The axon blue is surrounded by a fatty insulating sheath of myelin green which increases the speed of the nerve signal Nodes of Ranvier are areas of exposed axon with a high concentration of sodium channels Instead of travelling continuously along the length of the axon the impulse jumps between these nodes in a process called saltatory conduction This allows the impulse to travel over long distances
