NIME Next Batch PGI Quest in Delhi from 10 August to 20 August
B. It decreases gastric acid secretion
C. It decreases gastrin secretion and gastric emptying
D. Increases flow and velocity of bile
Which of the following is not true about secretin?
A. It increases the acidity of biliary and pancreatic secretionsB. It decreases gastric acid secretion
C. It decreases gastrin secretion and gastric emptying
D. Increases flow and velocity of bile
Ans. A. (It increases the
acidity of biliary and pancreatic secretions)
Explanation
• Secretin is secreted by S cells that are located deep in the glands of the mucosa of the upper portion of the small intestine. The structure of secretin is different from that of CCK and gastrin but very similar to that of glucagons, GLI, VIP, and GIP. Only one form of secretin has been isolated, and the fragments of the molecule that have been tested to date are inactive. Its half-life is about 5 minutes, but little is known about its metabolism. Secretin increases the secretion of bicarbonate by the duct cells of the pancreas and biliary tract. It thus causes the secretion of a watery, alkaline pancreatic juice. Its action on pancreatic duct cells is mediated via cAMP. It also augments the action of CCK in producing pancreatic secretion of digestive enzymes. It decreases gastric acid secretion and may cause contraction of the pyloric sphincter.
• Secretin is secreted by S cells that are located deep in the glands of the mucosa of the upper portion of the small intestine. The structure of secretin is different from that of CCK and gastrin but very similar to that of glucagons, GLI, VIP, and GIP. Only one form of secretin has been isolated, and the fragments of the molecule that have been tested to date are inactive. Its half-life is about 5 minutes, but little is known about its metabolism. Secretin increases the secretion of bicarbonate by the duct cells of the pancreas and biliary tract. It thus causes the secretion of a watery, alkaline pancreatic juice. Its action on pancreatic duct cells is mediated via cAMP. It also augments the action of CCK in producing pancreatic secretion of digestive enzymes. It decreases gastric acid secretion and may cause contraction of the pyloric sphincter.
• The secretion of secretin is
increased by the products of protein digestion and by acid bathing the mucosa
of the upper small intestine. The release of secretin by acid is another
example of feedback control: secretin causes alkaline pancreatic juice to flood
into the duodenum, neutralizing the acid from the stomach and thus inhibiting
further secretion of the hormone.
