We're going to discuss the way that our blood actually moves within the four chambers of the heart. So let's begin with stage number one. Now, in stage number one, stage number two, and stage number three, we're taking a cross section of the heart so that we expose the four different chambers. And we're examining the heart from a front side perspective. So we have the right side of the heart and the left side of the heart. Now, the right side of the heart contains the right pump that had the right atrium this chamber here, and the right ventricle, this chamber here, while the left side of the pump contains this left pump that contains our left atrium and our left ventricle.