In gastric secretion, gastrin acts on ________ receptor on parietal cells
**Core Concept**
Gastrin is a peptide hormone that stimulates gastric acid secretion in the stomach. It acts on specific receptors on parietal cells to increase the production of gastric acid, which is essential for digestion. The interaction between gastrin and its receptor plays a crucial role in regulating the gastric acid secretion.
**Why the Correct Answer is Right**
Gastrin acts on the CCKB (Cholecystokinin B) receptor, also known as the gastrin receptor, which is located on the parietal cells in the stomach. When gastrin binds to this receptor, it activates a G-protein coupled signaling pathway that increases the production of gastric acid. This is achieved through the activation of H+/K+ ATPase, also known as the proton pump, which pumps hydrogen ions into the stomach lumen. The increased acid production is essential for protein digestion and absorption of nutrients.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because gastrin does not act on the M3 muscarinic receptor, which is primarily involved in the parasympathetic innervation of the stomach and stimulates gastric acid secretion through a different mechanism.
* **Option B:** This option is incorrect because gastrin does not act on the H2 receptor, which is involved in the regulation of gastric acid secretion but is not the primary target of gastrin.
* **Option C:** This option is incorrect because gastrin does not act on the dopamine receptor, which is involved in the regulation of gastrointestinal motility and secretion but is not directly involved in gastric acid secretion.
**Clinical Pearl / High-Yield Fact**
Gastrin is also involved in the regulation of gastric emptying and intestinal motility, and its release is stimulated by the presence of amino acids and other nutrients in the duodenum.
**Correct Answer:** C. CCKB (Cholecystokinin B) receptor.