And eventually we have this repolarization period and then we return to our normal resting membrane potential of negative 90 millivolts. Now, what is the function of this plateau phase? Why would we want a longer depolarization period? So basically what the longer depolarization period does is it increases the time of contraction and that allows all the adjacent cardiac muscle cells to basically depolarize uniformly and quickly so that our heart basically contracts in a single and forceful steady contraction. And that ultimately allows the movement of the blood that carries the nutrients and the oxygen through the different parts of our body. So the reason we want the voltage gated calcium channels to basically exist is to create this longer contraction to allow all the adjacent cardiac cells to depolarize uniformly, to create this long and steady, uniform, forceful contraction of our heart.