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In the alveoli, oxygen from the air is absorbed into the blood. Carbon dioxide, a waste product of metabolism, travels from the blood to the alveoli, where it can be exhaled. Between the alveoli is a thin layer of cells called the interstitium, which contains blood vessels and cells that help support the alveoli.
Gas exchange. We need to get oxygen from the air into the blood, and we need to remove waste carbon dioxide from the blood into the air. Moving gases like this is called gas exchange. The alveoli are adapted to make gas exchange in lungs happen easily and efficiently.Here are some features of the alveoli that allow this:they give the lungs a really big surface area. they have moist, thin walls (just one cell thick). they have a lot of tiny blood vessels called capillaries.he alveoli are adapted to make gas exchange in lungs happen easily and efficiently. Here are some features of the alveoli that allow this: they give the lungs a really big surface area. they have moist, thin walls (just one cell thick). they have a lot of tiny blood vessels called capillaries.