Physiology of the alveolar surface network.

The alveolar surface network (ASN) is the totally fluid intraacinar conformation of the alveolar surface liquid (ASL) continuum circulating, both in series and in parallel, through ultrathin (to <7 nm) molecular conduits formed by appositions of unit bubbles of alveolar gas. The ASN is the analogue of foam in vitro. Appositions of unit bubble films, namely foam films, include (a) bubble-to-bubble at the alveolar entrance, across alveolar ducts, and at pores of Kohn ('classical foam films'); (b) bubble-to-epithelial cell surface ('cell-surface foam film'); and (c) bubble-to-open surface liquid layer of the terminal conducting airways ('surface foam film').

Structure and surface energy of the surfactant layer on the alveolar surface: inaccuracies and their correction.

The article of Kashchiev and Exerowa (Eur Biophys J 30:34-41) is shown to incorporate a number of inaccuracies that fit the categories "historical", "anatomical", and "biophysical". These inaccuracies are corrected by reference to published research reports from 1978 to 1998. The monolayer-bilayer model proposed by Kashchiev and Exerowa may be thermodynamically correct in vitro, but has not been related to the structure of the alveolar surface in vivo, which is that of a foam ("the alveolar surface network").