So we have these facilitated transfer proteins. We have the ones that transport our potassium from the inside to the outside, from a high to a low concentration. And we have these transfer proteins that transport our sodium from the high from the outside to the low to the inside. And we also have proteins that actually actively transport our potassium and sodium. And we're going to discuss these in much more detail in the next several lectures. This is known as the ATPase protein.