And so what that causes is it causes the right atrium and left atrium to contract at the same exact time. Now, as they begin to contract, they begin to move that blood into these ventricles of the heart. Now, as these electrical signals come to the AV node, the atrial ventricular node found in the interatrial septum in this section right here, that AV node delays that signal ever so slightly. And that is to make sure that all that blood efficiently flows into the ventricles of the heart. Once our delay takes place, the depolarization within the AV bundle takes place and that generates an action potential that moves via the bundle of his. And then it splits into the left and right bundle and then even more splitting takes place until we get to our perkinji fibers.