So the stomach serves a purpose in storage as well as in digestion. It typically has a capacity of two liters and is composed of special types of cells that serve several important functions. For example, we have parietal cells that secrete the hydrochloric acid and make our stomach acidic. So the acidity of the stomach is about two. And this activates special types of proteolytic enzymes that begin the breakdown of proteins into their smaller constituents. Now, although some substances, such as alcohol can be absorbed by the cells of the stomach, the stomach acts mostly in mechanical and chemical digestion.