Two important molecules stimulate parietal cells, so g cells secrete gastroin which stimulates parietal cells and our interchromethanlike cells also secrete a molecule known as histaminene that also stimulates the parietal cells to release our hydrochloric acid. And then the parietal cells, by releasing the hydrochloric acid, basically stimulate the chief cells to release our pipsinogen, which is then transformed into pepsin as a result of that hydrochloric acid as a result of that relatively low PH. So what can we actually conclude about the functionality and the purpose of our stomach? So we see that in our stomach we have the process of mechanical digestion taking place as a result of that continuous movement of our fluid and the contraction of our smooth muscle in our stomach that allows mechanical digestion to actually take place. So we further break down our food into smaller particles. Now inside our stomach we also break down our macromolecules.