CCK is released by specific cells in the body, mainly in response to a meal. Let's delve into the details of what triggers CCK release.
Sources of CCK Release
CCK, or cholecystokinin, is a hormone vital for digestion. It's not just released by one type of cell, but from a few key sources:
- Enteroendocrine Cells (I Cells): These are the primary source, located in the mucosal lining of the small intestine. Specifically, they're concentrated in the duodenum and jejunum. These I cells act as sensors, responding directly to the contents of digested food.
- Neurons of the Enteric Nervous System: These neurons also contribute to CCK release. They form part of the intrinsic nervous system of the gastrointestinal tract.
- Neurons in the Brain: Certain neurons within the brain also release CCK, although the exact mechanisms and roles are more complex and still being researched.
Stimuli for Release
The primary trigger for CCK release is the presence of food, particularly fats and proteins, in the duodenum. Here is a more detailed breakdown:
| Stimulus | Mechanism | Result |
|---|---|---|
| Fats | Presence of fatty acids and monoglycerides in the duodenum | Strongest trigger for CCK release |
| Proteins | Presence of peptides and amino acids in the duodenum | Moderate trigger for CCK release |
| Acidic Chyme | Presence of acidic stomach contents in the duodenum | Acts as a weaker stimulus for CCK release |
These stimuli activate the I cells, enteric neurons, and brain neurons, causing them to release CCK into the bloodstream. This is a rapid process that occurs soon after a meal enters the small intestine.
Summary of CCK Release
To put it simply:
- CCK is released by:
- I cells in the duodenum and jejunum
- Neurons in the enteric nervous system
- Neurons in the brain
- The release is primarily triggered by food, especially fats and proteins, entering the small intestine.
