The correct option is (A) Gastrin.
Stomach acts as an important organ in the process of digestion aiding both the mechanical and chemical digestion. Gastric glands are present in the walls of the stomach and help in the secretion of the gastric juice into the lumen of the stomach. The zymogenic cells or the chief cells of the gastric glands secrete the gastric enzymes and the parietal cells or the oxyntic cells secrete hydrochloric acid.
The gastric juice is an acidic digestive fluid containing the hydrochloric acid, digestive enzymes like pepsin, gastric lipase and renin, potassium chloride and sodium chloride. Secretion of gastric juice is regulated by the autonomic nervous system (peripheral nervous system that influcences the funtioning of internal organs) and hormones.
The hormone produced mainly in the stomach which regulates the secretions of gastric juice is the gastrin. It is a peptide hormone stimulating the secretion of hydrochloric acid by the parietal cells of the stomach. It also stimulates the chief cells to secrete pepsinogen which is the inactive form of the enzyme pepsin catalyzing the protein digestion.
Secretin is a hormone produced by the duodenum (part of small intestine) to stimulate the secretions of liver and pancreas. Pepsin is an enzyme helping in the digestion of proteins. Thus, gastrin is the hormone produced in the stomach regulating the secretion of the gastric juice.
