Questions and Answers
What are the primary paracrines found in the gastrointestinal tract?
Histamine decreases gastric $H^+$ secretion in the stomach.
False
What triggers the secretion of somatostatin in the gastrointestinal tract?
H+ in the lumen
Somatostatin inhibits the release of all GI __________.
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Match the paracrine to its action:
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Study Notes
Paracrines in the Gastrointestinal Tract
- Paracrines are signaling molecules released by endocrine cells in the gastrointestinal (GI) mucosa.
- They diffuse over short distances to target cells within the GI tract.
- Key GI paracrines include somatostatin and histamine.
Somatostatin
- Secreted by cells throughout the GI tract in response to hydrogen ions ($H^+$) present in the lumen.
- Vagal stimulation inhibits the secretion of somatostatin.
- Functions to inhibit the release of all gastrointestinal hormones, effectively regulating digestive processes.
- Also inhibits gastric secretion of hydrogen ions ($H^+$), reducing acidity in the stomach.
Histamine
- Secreted by mast cells found in the gastric mucosa.
- Increases gastric secretion of hydrogen ions ($H^+$) directly.
- Enhances the effects of gastrin, a hormone that stimulates gastric acid secretion, and vagal stimulation, promoting digestive function.
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Description
This quiz covers the role of paracrines in the gastrointestinal tract, focusing on somatostatin and histamine. It explores their secretion mechanisms, functions, and effects on GI hormones and secretions. Test your knowledge about these important signaling molecules.
