Gastric Acid and Digestive Physiology

The primary function of the stomach is to prepare food for digestion and absorption by the intestine. Although various neural and hormonal mediators contribute to gastric function, acid production is the unique and central component of the stomach’s contribution to the digestive process. Liquids pass easily through the stomach and into the small intestine. Solid components remain in the stomach until they are small enough to be slowly released into the small intestine by the coordinated action of the antrum and pylorus. Acid bathes the food bolus while stored in the stomach, facilitating digestion. An intact defense against mucosal damage by the stomach’s acid is essential to avoid ulceration. This article focuses on the physiology of gastric acid production, the stomach’s defense mechanisms against acid injury, and the most common challenges to the gastric defenses. A brief description of the stomach’s nonacid digestive capabilities is included.