And that's exactly why the surface tension drops. So this means that the water molecules can rotate and move much more freely than before. And this lowers their ability to withstand any force because once we apply force, they simply move around that force and so our surface tension drops. So by adding a detergent, a molecule that contains hydrophobic and hydrophilic properties into our water, into our liquid, we decrease our surface tension as a result of this concept. And this is exactly what happens inside the alveoli of our lungs. So within the lungs are microscopic balloon like structures called alveoli.