Correct Option
Gastrin is a peptide hormone, not a digestive enzyme. It is primarily produced by G cells in the pyloric antrum of the stomach. Its main function is to stimulate the secretion of hydrochloric acid (HCl) by the parietal cells and pepsinogen by the chief cells in the stomach, thereby regulating gastric motility and secretion. While it plays a crucial role in the digestive process, it does not directly catalyze the breakdown of food molecules.
Incorrect Options
- Trypsin is a proteolytic enzyme secreted by the pancreas as an inactive zymogen called trypsinogen. It is activated in the small intestine and functions to break down proteins into smaller peptides.
- Ptyalin, also known as salivary amylase, is a carbohydrate-digesting enzyme present in saliva. It initiates the digestion of starch in the mouth, breaking it down into simpler sugars like maltose.
- Pepsin is a proteolytic enzyme secreted by the chief cells of the stomach as an inactive zymogen called pepsinogen. It is activated by hydrochloric acid in the stomach and begins the digestion of proteins into smaller polypeptides.