See how sodium diffusion creates a local current that depolarizes the next axon region; refractory membrane behind the impulse supports one-way propagation.
Multicellular organisms benefit from cell specialization and division of labour.
Describe what occurs in a neuron when an action potential is propagated along the axon.
sodium ions/ Na+enter/diffuse in;
depolarization/membrane potential/voltage changes from negative to positive;
potassium channels open AND potassium ions /K+exit /diffuse out;
repolarization/membrane potential/voltage changes back from positive to negative;
local current due to diffusion of sodium ions along the neuron;
(local currents) cause next sodium channels to open/next part of axon to depolarize;
opening of sodium channels triggered when threshold potential/ -50 mV reached;