open to the esophagus. In more basal bony fish, such as the gar, bichir, bowfin and the lobe-finned fish, the bladders have evolved to primarily function as lungs. The lobe-finned fish gave rise to the land-based tetrapods. Thus, the lungs of vertebrates are homologous to the gas bladders of fish (but not to their gills). See also Atelectasis Drowning Interstitial lung disease Liquid breathing Lung abscess Lung-on-a-chip Secarecytosis List of terms of lung size and activity References Further reading Dr D.R. Johnson: Introductory anatomy, respiratory system, leeds.ac.uk Franlink Institute Online: The Respiratory System, sln.fi.edu Avian lungs and respiration, people.eku.edu External links Lung at the Human Protein Atlas Human anatomy by organ Articles containing video clips