Secretin

Definition

Secretin is a hormone produced by the S cells of the duodenum in the small intestine, primarily responsible for regulating the pH of the small intestine by stimulating the pancreas to release bicarbonate. This action neutralizes stomach acid that enters the duodenum, creating an optimal environment for digestive enzymes to function effectively. Secretin also plays a role in regulating water homeostasis and maintaining overall digestive health.

5 Must Know Facts For Your Next Test

1. Secretin was discovered in 1902 and was the first hormone identified in the human body.
2. This hormone is released in response to acidic chyme entering the duodenum from the stomach, helping to maintain an optimal pH for digestive enzymes.
3. In addition to stimulating bicarbonate secretion, secretin also influences gastric motility and slows down gastric emptying.
4. The action of secretin helps protect the lining of the intestine from acid damage by neutralizing stomach acid.
5. Secretin has been shown to have additional roles beyond digestion, such as modulating water balance and potentially influencing insulin secretion.

Review Questions

• How does secretin contribute to maintaining an optimal pH in the small intestine during digestion?
  • Secretin plays a crucial role in regulating the pH of the small intestine by stimulating the pancreas to release bicarbonate. When acidic chyme from the stomach enters the duodenum, secretin is released from S cells in response. The bicarbonate neutralizes this acid, creating a more alkaline environment that is necessary for digestive enzymes to function effectively, thus facilitating proper digestion.
• Discuss the relationship between secretin and other hormones involved in digestion, particularly cholecystokinin (CCK).
  • Secretin and cholecystokinin (CCK) work together to promote effective digestion in the small intestine. While secretin stimulates bicarbonate release from the pancreas to neutralize stomach acid, CCK is released in response to fatty acids and amino acids, promoting bile secretion from the gallbladder and stimulating pancreatic enzyme secretion. Together, these hormones coordinate digestive processes, ensuring that both pH balance and nutrient breakdown occur optimally.
• Evaluate how secretin's functions extend beyond digestion and what implications this may have for overall health.
  • While secretin is primarily known for its role in digestive regulation through bicarbonate secretion, it also has broader implications for overall health. Recent studies suggest that secretin may influence water balance in the body and play a role in insulin regulation. By understanding these additional functions, we can appreciate how hormones like secretin contribute not just to digestion but also to metabolic processes, highlighting their importance in maintaining homeostasis within the body.

Related terms

Bicarbonate: A chemical compound that acts as a buffer to maintain pH levels; secreted by the pancreas under the influence of secretin.

Pancreas:

An organ that produces digestive enzymes and hormones, including insulin and glucagon, and responds to secretin by releasing bicarbonate.

Cholecystokinin (CCK): A hormone released by the small intestine that works alongside secretin to promote digestion by stimulating bile release and enzyme secretion from the pancreas.