<Tr> <Th> TH </Th> <Td> H3. 05.02. 0.00026 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> A pulmonary alveolus (plural: alveoli, from Latin alveolus, "little cavity") is a hollow cavity found in the lung parenchyma, and is the basic unit of ventilation . Lung alveoli are the ends of the respiratory tree, branching from either alveolar sacs or alveolar ducts, which like alveoli are both sites of gas exchange with the blood as well . Alveoli are particular to mammalian lungs . Different structures are involved in gas exchange in other vertebrates . The alveolar membrane is the gas exchange surface . Carbon dioxide rich blood is pumped from the rest of the body into the capillaries that surround the alveoli where, through diffusion, carbon dioxide is released and oxygen absorbed . </P> <P> The alveoli are located in the respiratory zone of the lungs, at the ends of the alveolar ducts and alveolar sac, representing the smallest units in the respiratory tract . They provide total surface area of about 75 m . </P>

Where is the alveoli located in the respiratory system
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