NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,881 terms related to cancer and medicine.

Browse the dictionary by selecting a letter of the alphabet or by entering a cancer-related word or phrase in the search box.

alveoli
(al-VEE-oh-ly)
Tiny air sacs at the end of the bronchioles (tiny branches of air tubes) in the lungs. The alveoli are where the lungs and the bloodstream exchange carbon dioxide and oxygen. Carbon dioxide in the blood passes into the lungs through the alveoli. Oxygen in the lungs passes through the alveoli into the blood.