the.com/alveolus
the tiny air balloon where your blood meets the sky and trades gasses
means A tiny hollow sac in the lungs where oxygen and carbon dioxide pass between the air you breathe and your blood, though the word also covers other small cavities like tooth sockets.
from From Latin alveolus, the diminutive of alveus, "a hollow, cavity, or trough" — so literally a "little hollow." Alveus itself comes from alvus, "belly" or "cavity," giving us the sense of a small scooped-out space. The same root surfaces in "alveolar," the ridge behind your teeth that shapes certain consonants.
- count
- around 300 million per pair of lungs
- surface area
- unfolded, they cover a tennis court
- wall thickness
- thinner than a single tissue paper sheet
- slick coating
- surfactant keeps them from collapsing shut
pulmonary alveoli — 300 million gas-exchange sacs in human lungs, where oxygen enters blood
dental alveolus — socket in jawbone that holds tooth roots, found in maxilla and mandible