Question

Secretin and cholecystokinin are the hormones secreted in
A) Pyloric stomach
B) Duodenum
C) Ileum
D) Oesophagus

Answer 1

Hormones are chemical substances which are required for proper functioning and growth of the body. Secretin and cholecystokinin are hormones which are secreted in response to acidity and helps in digestion of fat and protein respectively.

Complete answer:
Secretin is a digestive hormone. It is secreted by the intestinal wall in the duodenum. It is stimulated by food and the strong acid in the stomach and intestine. Secretin is released into the bloodstream when hydrochloric acid passes from the stomach into the duodenum. It targets the pancreas, secretory cells and muscles of the stomach. It is responsible for the secretion of water and bicarbonate $NaHC{{O}_{3}}$ . It inhibits gastric motility by inhibiting the secretion of gastrin.

Cholecystokinin is a digestive hormone that is released with secretion. It is secreted by cells of the upper small intestine (duodenum). It is stimulated by food (fatty chyme and amino acids) in the duodenum. It targets the gallbladder to contract and release bile juice into the intestine. It also targets the pancreas to secrete pancreatic juice. When food leaves the stomach through its pyloric end and enters the duodenum it is called chyme (acidic). The $HCl$ of chyme stimulates the wall of the duodenum to secrete hormones. It secretes various hormones, for example, secrein, which is the most important hormone of the digestive tract and is released by the duodenum.

This hormone stimulates the pancreas for synthesis and secretion of the non-enzymatic part of pancreatic juice. It also stimulates the liver for the secretion of bile juice and inhibits gastric acid secretion in the stomach and reduces the rate of contraction of the stomach.

Hence the correct answer is ‘B’.

Note: Pancreatic secretions are also the major mechanism for neutralizing gastric acid in the small intestine. The pancreatic juice contains digestive enzymes and bicarbonate which are secreted from exocrine acinar cells and epithelial cells of pancreatic ducts respectively.