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The AP cycle

threshold of excitation is reach and sodium channels in membrane open

Na+ rushes in, propelled by forces of diffusion and electrostatic pressure

opening of channels is triggered by reduction of membrane potential (depolarisation), opening at the point where AP begins

channels have opened which changes he membrane potential, known as voltage dependent ion channels.

Channel (voltage-dependent ion channels) opens= change in membrane potential. Influx of Na+ produced change of membrane potential from -70mV to 40+mV.

The axon membrane contains VDPC, but these channels are less sensitive than VDSC due to the greater level of demoralisation needed before they open= they open later than sodium channels