Law of Laplace

  • The Law of Laplace is a physical law discovered by the great French mathematician Piere-Simon Laplace (and others) which describes the pressure-volume relationships of spheres. It is used to understand physiological features of both the heart and alveoli thus justifying its categorization as a basic concept.
Law of Laplace
  • Pressure = (2 x Thickness x Tension)/Radius
  • Where
    • Pressure = The pressure inside the sphere
    • Thickness = Thickness of the sphere's wall
    • Tension = Tension within the sphere's wall
  • The Law of Laplace essentially states that the tension within the wall of a sphere filled to a particular pressure depends on the thickness of the sphere. Consequently, even at a constant pressure, the tension within a filled sphere can be decreased simply by increasing the thickness of the sphere's wall.