Advanced Dental Admission Test (ADAT)

What stimulates parietal cells to secrete HCl?

1. Secretin

2. Pepsinogen

3. Gastrin

4. Intrinsic factor

The correct answer is: Gastrin

Parietal cells, located in the gastric mucosa, are primarily responsible for the secretion of hydrochloric acid (HCl), which plays a crucial role in the digestive process. The primary stimulant for these cells to secrete HCl is gastrin, a peptide hormone produced by G cells in the stomach in response to the presence of food. When food enters the stomach, it stretches the stomach wall and stimulates certain cells to release gastrin into the bloodstream. Gastrin travels to the parietal cells and binds to specific receptors, thereby activating intracellular signaling pathways that lead to the secretion of HCl. This acid helps to create the acidic environment necessary for optimal digestion and also activates pepsinogen, enabling it to convert to pepsin, a key digestive enzyme. In contrast, secretin is released primarily from the small intestine and functions to regulate the pH of the small intestine by promoting the secretion of bicarbonate from the pancreas, rather than stimulating HCl secretion. Pepsinogen is an inactive precursor of pepsin and is not responsible for stimulating HCl production, but rather it is activated when exposed to acidic conditions created by HCl. Intrinsic factor, another secretion from parietal cells, is essential for the