And we have these two semi lunar valves. We have the pulmonary semi lunar valve and we have the aortic semi lunar valve. So let's begin with stage number one. In stage number one, the atrium of the heart, and that includes the right atrium and the left atrium, are fully relaxed. And at this moment in time, they both receive blood from the rest of our body. So let's begin with the right pump that contains the right atrium.