Final answer:
Oxygenated blood from the lungs flows to the heart, specifically entering the left atrium, and is then pumped into the left ventricle before it circulates through the body.
Step-by-step explanation:
In humans, oxygenated blood from the lungs flows directly to the heart and enters the left atrium. From the left atrium, the blood is then pumped into the left ventricle. The left ventricle then contracts, sending the oxygenated blood into the aorta and subsequently to the rest of the body in the systemic circuit. This efficient process allows for the exchange of gases in the lungs and the delivery of oxygen-rich blood to the body's tissues and organs.