Lung surfactants are lipoprotein complexes which are formed by type 2 alveolar cells. The main lipid component, known as dipalmitoylphosphatidylcholine, is known to reduce surface tension in the lung.
 
 
Recommended Resources
Development of Synthetic Lung Surfactants
The Journal of Lipid Research presents this paper regarding how lung surfactants are developed using organic solvent extract of natural bovine lung tissue.
http://www.jlr.org/cgi/content/abstract/27/5/475
Keeping Lung Surfactant Where It Belongs: Protein Regulation of Two-Dimensional Viscosity
Biophysical Journal article which discusses surfactant and surface tension in the alveoli, offers this information in PDF format, full text with thumbnail figures and citations. Also contains other articles by these authors.
http://www.cell.com/biophysj/abstract/S0006-3495%2805%2972676-X
Exhibits informal lecture notes which assist in introducing physicists to biological surfactants. Subtopics include surfact tension in the lungs, pulmonary surfactant proteins, and theory of pulmonary surfactant dynamics.
http://ising.cwru.edu/surfactants/