So let's begin by taking a look at a cross section of the heart, as shown in this diagram. So we have the right side of the heart. We have the left side of the heart. This is our superior and inferior vena cava, the right atrium, the right ventricle, the left atrium, the left ventricle. We have the pulmonary arteries that extend into the lungs. And we have our order that splits into the ascending and descending a order.