Outline the passage of air through the respiratory system?

Air enters the respiratory system through the nose or mouth, where it is filtered, warmed, and humidified. It then travels down the trachea, which divides into the bronchi leading to each lung. Within the lungs, air moves into smaller bronchioles and reaches the alveoli, tiny air sacs where gas exchange occurs. Oxygen is absorbed into the bloodstream, and carbon dioxide is expelled from the blood to be exhaled.