Feedback Mechanism
The negative feedback mechanism of gastric acid secretion
A negative feedback loop in the digestive system occurs in which the low pH of the stomach inhibits gastrin secretion by the G cells which results in less acid secretion. Gastric acid aids digestion by creating the optimal pH for pepsin and gastric lipase and by stimulating pancreatic bicarbonate secretion. Acid secretion is initiated by food: the thought, smell, or taste of food effects stimulation of the gastrin-secreting G cells located in the distal one third (antrum) of the stomach. The parietal cells secrete acid, and the resulting drop in pH causes the antral D cells to release somatostatin, which inhibits gastrin release (negative feedback control).