Secretin

Definition

Secretin is a hormone produced by the S cells of the duodenum in the small intestine, primarily involved in regulating the pH of the digestive tract. It plays a crucial role in stimulating the pancreas to secrete bicarbonate-rich fluid, neutralizing stomach acid as it enters the small intestine, and also promotes bile secretion from the liver. This process is essential for optimal enzyme activity during digestion.

5 Must Know Facts For Your Next Test

1. Secretin is released in response to the presence of acidic chyme in the duodenum, signaling the need for neutralization.
2. The primary action of secretin is to stimulate the pancreas to release bicarbonate, which helps raise the pH of the intestinal contents.
3. In addition to its effects on the pancreas, secretin also stimulates bile production in the liver, aiding in fat digestion.
4. Secretin plays a role in promoting proper digestive enzyme function by ensuring that the small intestine's environment is not too acidic.
5. The discovery of secretin was significant in understanding hormonal regulation within the digestive system and how hormones control various digestive processes.

Review Questions

• How does secretin function in regulating the digestive process when acidic chyme enters the duodenum?
  • When acidic chyme from the stomach enters the duodenum, it triggers S cells to release secretin into the bloodstream. This hormone then stimulates the pancreas to secrete bicarbonate, which neutralizes stomach acid, creating an optimal pH for digestive enzymes to work. Additionally, secretin enhances bile production from the liver, further aiding in fat digestion and overall nutrient absorption.
• Discuss the interplay between secretin and cholecystokinin (CCK) in digestion and their respective roles.
  • Secretin and cholecystokinin (CCK) work together to coordinate digestive processes in response to food entering the small intestine. While secretin primarily regulates pH by stimulating bicarbonate secretion from the pancreas and bile production from the liver, CCK focuses on stimulating gallbladder contraction to release bile and promoting pancreatic enzyme secretion. This cooperation ensures that both acidic content is neutralized and that fats and proteins are efficiently digested.
• Evaluate the impact of secretin on digestive health and how abnormalities in its secretion could affect gastrointestinal function.
  • Secretin is crucial for maintaining proper digestive health by regulating pH levels in the small intestine and ensuring effective enzyme activity. Abnormalities in secretin secretion can lead to digestive issues such as malabsorption or excessive acidity in the intestines. For example, insufficient secretin may result in inadequate bicarbonate production, causing an overly acidic environment that hinders enzyme function, ultimately affecting nutrient absorption and leading to gastrointestinal disorders.

Related terms

Bicarbonate: A chemical compound that acts as a buffer to neutralize acids, primarily produced by the pancreas in response to secretin.

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

Duodenum: The first part of the small intestine where secretin is secreted and where significant chemical digestion occurs.