Cholecystokinin

Definition

Cholecystokinin (CCK) is a hormone produced in the small intestine that plays a critical role in digestion and metabolism. It is released in response to the presence of fats and proteins in the chyme, stimulating the gallbladder to contract and release bile, which is essential for fat digestion. Additionally, CCK signals the pancreas to secrete digestive enzymes, enhancing the digestive process and promoting satiety after meals.

5 Must Know Facts For Your Next Test

1. Cholecystokinin is secreted by I cells located in the mucosa of the duodenum when fatty acids and amino acids are detected.
2. In addition to stimulating bile release, CCK slows gastric emptying to allow for more efficient digestion and absorption of nutrients.
3. CCK has a role in promoting feelings of fullness (satiety), helping to regulate food intake and energy balance.
4. The action of CCK is part of a complex feedback system that includes other hormones like secretin and ghrelin, which help manage digestion and hunger.
5. Abnormal levels of cholecystokinin have been associated with digestive disorders and obesity, indicating its importance in maintaining digestive health.

Review Questions

• How does cholecystokinin affect digestion and what role does it play in regulating bile release?
  • Cholecystokinin affects digestion by stimulating the gallbladder to contract and release bile into the small intestine. This bile is crucial for emulsifying fats, making them easier to digest. The release of CCK occurs when fatty acids and amino acids enter the small intestine, ensuring that fats are properly processed alongside other nutrients. This coordination enhances overall digestion and nutrient absorption.
• Discuss the relationship between cholecystokinin, gastric emptying, and satiety after meals.
  • Cholecystokinin not only stimulates bile release but also plays a significant role in slowing gastric emptying. By delaying the movement of food from the stomach into the small intestine, CCK allows for more thorough digestion and nutrient absorption. Furthermore, CCK contributes to feelings of satiety after meals, signaling to the brain that enough food has been consumed. This interplay helps regulate overall food intake and maintain energy balance.
• Evaluate how abnormalities in cholecystokinin levels might impact health and contribute to digestive disorders or obesity.
  • Abnormal levels of cholecystokinin can significantly impact health by disrupting normal digestive processes. Low levels may lead to insufficient bile release, impairing fat digestion and absorption, while high levels can cause excessive gallbladder contraction or gastrointestinal discomfort. In terms of obesity, imbalances in CCK may affect satiety signals, leading individuals to overeat. Understanding these connections highlights the importance of maintaining healthy hormone levels for optimal digestive health.

Related terms

Bile:

A digestive fluid produced by the liver and stored in the gallbladder, bile helps emulsify fats in the small intestine.

Pancreatic enzymes: Digestive enzymes produced by the pancreas that break down carbohydrates, proteins, and fats in the small intestine.

Ghrelin: A hormone produced primarily in the stomach that stimulates appetite and promotes food intake, often referred to as the 'hunger hormone.'