Now together the bundle of his and these perkinji fibers basically distribute that electrical signal through the bowl, through the two ventricles of the heart and it causes these two ventricles to actually contract at the same time, simultaneously. So, once again, the electrical signal is generated within the SA node, which is found in the upper right atrium of the heart. And as this electrical signal is generated, it moves not only through these conduction fibers found within the right atrium, but it also moves through specialized conduction fibers known as the back men's bundle, which travels through the left atrium of the heart. 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.