Osmosis video - Law of Laplace

The law of Laplace is a law in physics that states that the wall tension of a hollow sphere or cylinder is proportional to both the pressure of its contents and its radius. Wall stress is the wall tension divided by 2 times the wall thickness. Now, when applied to hollow spherical objects like the left ventricle of the heart, the following formula is used: wall stress = P x r / 2w, where P is pressure, r is total radius, and w is wall thickness. Put simply, the law of Laplace states that wall tension is directly proportional to pressure and radius; and wall stress is proportional to the wall tension but inversely proportional to two times the wall thickness.