Alveolar surface tension and surfactant

Attractive forces between liquid surfactant molecules result in surface tension. Surfactants disrupt these attractions and therefore help prevent alveolar collapse and increase compliance.

Dipalmitoyl phosphatidylcholine is amphiphilic and is the major surfactant in alveoli. The amount of surfactant is controlled by type II pneumocytes. ''It also includes proteins. There is feedback between proteins and the pneumocytes.''

''Note that you wll have the same amount of surfactant in each alveolus. That means that the layer of surfactant will be thinner in larger alveoli, air''

see laplace law - f you had no surfactant, smaller alveoli would have greater pressure, then all the air would go to the larger one, and the larger will keep inflating but the smaller one wll collapse

but since there is surfactants, surface tension is decreased and pressure is equalized