And the essay note contains cells where the membrane of those cells depolarize. And that creates an electrical potential difference. And that's exactly why we have an increase in the voltage taking place within this portion. So when the SA node generates that electrical signal, the action potential, it increases the voltage, it makes it more positive. And our electrical signal then propagates through these conduction channels shown in purple. And these conduction channels extend through the right atrium and through the left atrium.