So here I said that we have the opening of these voltage gated sodium channels, but the voltage gated sodium channels are not the only ones to open. We also have the opening of the potassium voltage gated on channels. But these potassium voltage gate on channels are very, very slow to open. On the contrary, the sodium voltage gated on channels open up very, very quickly. And so that's exactly why we have this deep polarization period, a rapid increase to a positive value of that potential. So the opening of the voltage gated sodium channels leads to a rapid rise in the membrane potential.