Gastric acid network (called canaliculi) from which the hydrochloric acid is secreted into the lumen of the stomach. The pH of gastric acid is 1.5 to 3.5 in the human stomach lumen, the acidity being maintained by the proton pump H/K ATPase. The parietal cell releases bicarbonate into the bloodstream in the process, which causes a temporary rise of pH in the blood, known as an alkaline tide. The highly acidic environment in the stomach lumen causes proteins from food to lose their characteristic folded structure (or denature). This exposes the protein's peptide bonds. The gastric chief cells of the stomach secrete
Stomach carbohydrates, proteins, and fats. This allows the brain to link nutritional value of foods to their tastes. A series of radiographs can be used to examine the stomach for various disorders. This will often include the use of a barium swallow. Another method of examination of the stomach, is the use of an endoscope. A gastric emptying scan is considered the gold standard to assess gastric emptying rate. A large number of studies have indicated that most cases of peptic ulcers, and gastritis, in humans are caused by "Helicobacter pylori" infection, and an association has been seen with the development