Cholecystokinin

Definition

Cholecystokinin (CCK) is a peptide hormone produced by the cells in the intestinal lining that plays a vital role in digestion and appetite regulation. It is released in response to the presence of fats and proteins in the small intestine, promoting the release of digestive enzymes from the pancreas and stimulating the gallbladder to contract and release bile. This hormone not only aids in the digestion process but also acts as a satiety signal, helping to reduce hunger and regulate food intake.

5 Must Know Facts For Your Next Test

1. Cholecystokinin is secreted when partially digested food enters the small intestine, particularly when fats and proteins are present.
2. CCK not only aids digestion by stimulating bile release but also influences the central nervous system to promote feelings of fullness.
3. In addition to its effects on digestion, CCK can slow down gastric emptying, allowing for more efficient nutrient absorption.
4. The release of CCK is part of a feedback mechanism that helps maintain energy homeostasis by signaling when enough food has been consumed.
5. Imbalances in CCK levels can lead to issues with appetite regulation, potentially contributing to obesity or eating disorders.

Review Questions

• How does cholecystokinin contribute to the physiological mechanisms involved in satiety?
  • Cholecystokinin contributes to satiety by signaling the brain when sufficient food has been consumed. When CCK is released in response to fats and proteins in the small intestine, it activates receptors in the brain that promote feelings of fullness. Additionally, CCK slows gastric emptying and enhances digestive enzyme secretion, further supporting the sensation of satiety and reducing subsequent food intake.
• Discuss the interaction between cholecystokinin and other hormones like ghrelin and leptin in regulating hunger and energy balance.
  • Cholecystokinin works alongside hormones like ghrelin and leptin to regulate hunger and maintain energy balance. While ghrelin promotes appetite by signaling hunger from the stomach, CCK counteracts this signal by inducing feelings of fullness after eating. Leptin complements CCK's role by providing feedback on fat stores; high levels of leptin suppress appetite while low levels promote hunger. This interplay ensures a dynamic system that adjusts food intake based on current energy needs.
• Evaluate how disruptions in cholecystokinin signaling may impact body weight regulation and overall health.
  • Disruptions in cholecystokinin signaling can significantly impact body weight regulation and overall health. If CCK levels are too low, individuals may experience increased hunger and reduced feelings of fullness, leading to overeating and potential weight gain. Conversely, if CCK signaling is excessively heightened, it may contribute to reduced food intake and difficulties in maintaining adequate nutrition. These imbalances can increase the risk for obesity or eating disorders, highlighting the importance of proper CCK function in maintaining healthy eating patterns and metabolic health.

Related terms

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

Leptin:

Leptin is a hormone secreted by adipose (fat) tissue that helps to regulate energy balance by inhibiting hunger, thereby promoting satiety.

Peptide YY: Peptide YY is a hormone released by the intestines after eating, which helps to reduce appetite and inhibit gastric motility.