key term - Secretin

Definition

Secretin is a hormone produced by the S cells of the duodenum in response to acidic chyme entering the small intestine from the stomach. It plays a crucial role in regulating digestive processes by stimulating the pancreas to secrete bicarbonate-rich fluid and the liver to produce bile, thereby aiding in the neutralization of stomach acid and promoting optimal conditions for digestive enzymes.

5 Must Know Facts For Your Next Test

1. Secretin was discovered in 1902 by William Bayliss and Ernest Starling, making it one of the first hormones identified.
2. The release of secretin is triggered when acidic chyme enters the small intestine, helping to maintain a proper pH for enzyme activity.
3. In addition to stimulating pancreatic bicarbonate secretion, secretin also inhibits gastric acid secretion from the stomach.
4. Secretin works synergistically with cholecystokinin to enhance digestive processes, ensuring efficient breakdown and absorption of nutrients.
5. Dysregulation of secretin levels can lead to digestive disorders, such as pancreatitis or problems with fat digestion due to inadequate bile production.

Review Questions

• How does secretin contribute to maintaining an optimal environment in the small intestine for digestive processes?
  • Secretin contributes to maintaining an optimal environment in the small intestine by stimulating the pancreas to secrete bicarbonate-rich fluid, which neutralizes stomach acid. This creates a less acidic environment that is ideal for the action of digestive enzymes. By promoting bile production in the liver, secretin further assists in fat digestion, thus ensuring that nutrients can be effectively broken down and absorbed.
• What are the roles of secretin and cholecystokinin in regulating digestive processes, and how do they work together?
  • Secretin and cholecystokinin (CCK) both play essential roles in regulating digestive processes but act on different aspects. Secretin primarily stimulates bicarbonate secretion from the pancreas and bile production from the liver, neutralizing stomach acid. Meanwhile, CCK stimulates gallbladder contraction to release bile and promotes pancreatic enzyme secretion. Together, they coordinate a comprehensive response that optimizes digestion when food enters the small intestine.
• Evaluate how imbalances in secretin levels could affect digestion and overall health.
  • Imbalances in secretin levels can significantly impact digestion and overall health. If secretin is overproduced, it may lead to excessive bicarbonate secretion, disrupting normal digestive enzyme function and potentially causing diarrhea or malabsorption issues. Conversely, inadequate secretin production can result in insufficient bicarbonate and bile secretion, leading to problems like fat malabsorption or gastritis due to high acidity. Understanding these imbalances helps inform treatment strategies for related gastrointestinal disorders.

Related terms

Pancreatic Juice: A mixture of digestive enzymes and bicarbonate produced by the pancreas, essential for digestion and neutralizing stomach acid.

Bile: A digestive fluid produced by the liver and stored in the gallbladder, which aids in the emulsification of fats.

Cholecystokinin (CCK): A hormone released by the small intestine that stimulates gallbladder contraction and pancreatic enzyme secretion, complementing the action of secretin.