THE STOMACH

The stomach is the “J” shaped portion of the alimentary canal. It is where the food can be stored for up to 1-4 hours. Whilst the food is there it is constantly being mixed with gastric juice. This creamy mixture is known as chime. Along the lining of the stomach are epithelium cells, which consist also of mucus secreting cells and gastric glands which secrete hydrochloric acid and gastric juice.

The gastric juice is a combination of water, hydrochloric acid (secreted by the oxyntic cells), pepsiongen (enzyme pepsin, secreted by zymogenic / chief cells), prorennin, (secreted by chief cells in babies and very young), mucus (secreted by goblet cells).

Hydrochloric acid present in the stomach produces a pH of 1-2, which is necessary for the pepsin to work. The mucus which is secreted by cells in the gastric glands is done so in large volumes. The mucus forms a protective layer over the cells / lining in the stomach. This is to protect against pepsin, and strong hydrochloric acid in the gastric juice. These cells are reprocated every few days.

Also present in the stomach is another cell responsible for the secretion of gastrin into the blood system. Gastrin is produced and responsible by a hormone called gastrin. This also stimulates the secretion of pepsinogen and hydrochloric acid in the gastric juice, and the contractions of the stomach walls.