Final answer:
Once oxygenated, blood flows through the pulmonary veins to the left atrium, then through the mitral valve into the left ventricle.
Step-by-step explanation:
Once blood has been oxygenated, it travels through the pulmonary veins, through the left atrium, and then through the mitral valve before entering the left ventricle.
After this point, the oxygenated blood is pumped by the left ventricle through the aortic valve into the aorta, continuing to the systemic circuit to deliver oxygen to tissues throughout the body. The pulmonary veins are key in this process as they carry highly oxygenated blood into the left atrium, which directs blood flow into the left ventricle through the action of the mitral valve.