Action potentialOnline version Diagram showing the cycle action potential of a Neuron in action by Hannah Ronning 1 Resting potential -70 mV 2 Ion gate opens -> MPSP 3 Gate Threshold for action potential: -55mV 4 Peak action potential 5 Na+ channels close; K+ channels open; Na+K+ Pump 6 Moving toward repolarization 7 Absolute refractory period, 8 Relative refractory period