Voltage-gated channels and action potentials To explain the basics of action potentials, you only need to worry about K leak channels and two types of gated channels: Voltage-gated Na Channels: Open for about 0.5-1 msec in response to mild membrane depolarization, with the threshold for opening at about ?55 mV.Voltage-gated K Channels: Open for about 2-20 msec in response to moderate membrane depolarization, with the threshold for opening at ?30 to ?10 mV. Note that both channel types close automatically shortly after opening, but the voltage-gated K channels stay open longer. Question Let’s consider the hypothetical excitable described above with Na/K pumps, K leak channels, and the voltage-gated Na and K channels, and with the cell initially at a resting membrane voltage of about ?70 mV. Assume that an external stimulus momentarily brings the membrane voltage to ?55 mV. Place the items below in the most logical sequence of events that would follow the mild depolarization.