Source:http://linkedlifedata.com/resource/umls/id/C1515933
NCI: 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.,NCI: Any of the terminal sacs in the lungs through which gas exchange takes place with the pulmonary capillary blood.