Advanced Dental Admission Test (ADAT)

What cells in the small intestine produce secretin?

1. S Cells

2. I Cells

3. K Cells

4. Chief Cells

The correct answer is: S Cells

Secretin is a hormone that plays a crucial role in regulating water homeostasis and pH levels in the small intestine. It is produced by specialized cells known as S cells, which are located in the mucosal lining of the duodenum, the first segment of the small intestine. When acidic chyme from the stomach enters the duodenum, the S cells detect the low pH and respond by secreting secretin into the bloodstream. Upon its release, secretin stimulates the pancreas to release bicarbonate-rich fluid, which helps neutralize gastric acid. This creates a more favorable environment for the functioning of digestive enzymes in the small intestine. Additionally, secretin also acts on the liver to promote bile production, which is important for lipid digestion. The other cell types listed have distinct functions in the digestive system. I cells produce cholecystokinin (CCK), K cells release gastric inhibitory polypeptide (GIP), and chief cells secrete pepsinogen in the stomach. Thus, the action and significance of S cells in producing secretin are pivotal for maintaining the appropriate conditions for digestion in the small intestine.