Physiological applications of Laplace Law

In physiology, the Laplace Law describes the relationship between the pressure required to keep a spherical hollow organ open:

P = 2*T/r

For pressure P (dynes/cm2), surface tension T (dynes/cm), and the radius r (cm)

This means that to stay open, small organs require either a lot of pressure or decreased surface tension.

Such organs include not only to alveoli but also the heart and bladder.