Importance of surface tension in lung mechanics

Law of Laplace P= 2 T / R

P= 2 T / R

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Law of Laplace: the pressure inside a bubble is inversely proportional to the radius, due to the surface tension of fluid lining. This surface is created by the air-fluid interface. Bubbles with a small radius need large pressure to keep them inflated. Bubbles with a large radius need less pressure.

The effect of the Law of Laplace is more complex on alveoli because they are all interconnected, therefore if one tends to collapse it will expand neighbouring alveoli.