How it the resting potential established?

The sodium/potassium pump actively transports 3Na+ out of the axon for every 2K+ pumped in to the axon using ATP K+ diffuses back out of the cell down the chemical gradient through protein channels the K+ diffusion out of the cell is opposed by the electro gradient in the opposite direction - the K+ moving into the cell - so a resting potential of -70mV is achieved the membrane becomes less permeable to Na+ so less diffuses back into the cell