The solar lines move this way. The solar move this way, and electrons move the other way, and electrons move the other way. So a neuron cell is simply a complex version of a concentration cell. And the ions and electrons move in the same way in a cell membrane of a neuron cell as they do in a concentration cell. And now we can use this concentration cell set up with the oxidation reduction reactions to calculate our cell voltage or rustic potential due to these sodium ions. And let's do exactly that.