So we have the inferior venecrava and the superior venecrava. And as the partially oxygenated blood makes its way via these two blood vessels and into the right atrium, once inside the right atrium, that blood goes into the left atrium via the Foramin or valley. And that's because on the right side of the heart, we have a higher pressure than the left side as a result of those nonfunctional lungs. So the foramen or valley is like a one way door that opens this way because of a higher pressure being present inside the right atrium as compared to the left atrium. Now, a small amount of that blood will still make its way into the right ventricle. And when that right ventricle contracts, it will pump that blood into the pulmonary trunk.