G cells primarily secrete gastrin.
Gastrin-Secreting Cells: An In-Depth Look
Gastrin is a crucial hormone in the digestive system, stimulating the secretion of gastric acid (HCl) by parietal cells in the stomach. Understanding which cells produce gastrin is key to understanding the regulation of gastric function.
Primary Source: G Cells
- Location: According to the provided reference, the main source of gastrin is G cells, located predominantly in the gastric antrum (the lower part of the stomach) and, to a lesser extent, in the upper duodenum (the first part of the small intestine).
- Function: These specialized cells are designed to synthesize, store, and release gastrin in response to various stimuli, such as:
- The presence of peptides and amino acids in the stomach.
- Vagal stimulation (via the vagus nerve).
- Stomach distension.
Ectopic Production: APUD Tumors
In rare cases, gastrin can be produced by tumors outside of the typical locations within the GI tract. The reference mentions that gastrin may be produced ectopically by any APUD-type tumour, especially those occurring in the pancreas and duodenum. APUD stands for Amine Precursor Uptake and Decarboxylation; APUD cells are a group of endocrine cells with common cytochemical characteristics. When tumors arise from these cells, they sometimes retain the ability to produce hormones, in this case, gastrin. This ectopic production can lead to conditions like Zollinger-Ellison syndrome, characterized by excessive gastric acid secretion and peptic ulcers.
Summary Table
| Cell Type | Primary Location | Primary Function | Potential for Ectopic Production |
|---|---|---|---|
| G cells | Gastric antrum, upper duodenum | Gastrin secretion in response to stimuli | No |
| APUD-type tumour | Pancreas, duodenum (ectopic) | Ectopic gastrin secretion | Yes |
