AP BIOLOGY

Detailed explanation-1: -During gas exchange oxygen moves from the lungs to the bloodstream. At the same time carbon dioxide passes from the blood to the lungs. This happens in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli.

Detailed explanation-2: -As the alveoli is rich in oxygen and tissues are rich in carbon dioxide(as oxygen is utilized there and carbon dioxide is released as a byproduct ), the gases get exchanged by diffusion along the concentration gradient. So, the gases get interchanged in between the lung and the tissues.

Detailed explanation-3: -The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out. Oxygen breathed in from the air passes through the alveoli and into the blood and travels to the tissues throughout the body.