Morphological and physical basis for lung surfactant action.

An abhesive or 'anti-glue' function for lung surfactant is proposed which is reconcilable with the known unfolding of alveolar walls at low lung volumes. The theory is developed based upon the fact that the work required to part wetted surfaces is directly proportional to the surface tension. Application of the concept of the spreading coefficient from surface physical chemistry S = gammata-(gamma lla + gamma lle), where the gamma's refer to the surface (interfacial) tensions among the tissue (t), air (a) and lining layer (ll) surface, is shown to explain qualitatively physiological data in lungs subjected to maneuvers with working fluids varying widely in surface tension and spreading properties.