First, blood returns from the bottom to the descending aorta. 2. That blood is dumped into the right atrium. 3. It goes through tricuspid valve into the right ventricle. 4. From the right ventricle is goes into the pulmonary artery with deoxygenated blood. 5. Blood goes into the lungs for oxygen/carbon dioxide exchange in the capillaries. 6. Once blood is oxygenated again, it returns to the heart via the pulmonary vein. 7. The pulmonary vein dumps into the left atrium. 8. From the left atrium it descends through the mitral valve into the left ventricle. 9. After it's in the left ventricle, it goes into the ascending aorta and back out into the body.
