Fundus of the Stomach
The fundus of the stomach is the left portion of the stomach's body, and is marked off from the remainder of the body by a plane passing horizontally through the cardiac orifice. It contains rugae folds to help with expansion, which the main function of the fundus (to expand to make room for more food). The rugae contains several specialized cells to help aid in digestion including parietal cells (HCl- Hydrochloric acid production by releasing H+ and Cl-), Chief cells (pepsin production by releasing pepsinogin which reacts with HCl to make pepsin), and Mucus cells (to release mucus and coat the stomach, protecting it from the low pH, high acid environment). As the rounded part of the upper stomach, it allows for an accumulation of stomach gases produced by chemical digestion. It will also store undigested food for up to 1 hour.