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. Now, they resemble balloons in that we actually have to apply a certain pressure to inflate them. But when we release that pressure, when the pressure is removed, the elasticity of our balloons causes them to actually deflate and return back to their original shape. So let's take a look at the following microscopic sections.