The main pathway for the oxygenation of blood in the lungs occurs in the alveoli, where blood undergoes gas exchange. Oxygen from inhaled air diffuses through the alveolar walls into the surrounding capillaries, where it binds to hemoglobin in red blood cells. At the same time, carbon dioxide is released from the blood into the alveoli to be exhaled. This efficient exchange is essential for delivering oxygen to tissues and removing waste gases from the body, sustaining cellular respiration.