What is the normal PH of stomach juice and what regulates it?

The normal pH of stomach juice typically ranges from 1.5 to 3.5, making it highly acidic. This acidity is primarily regulated by the secretion of gastric acid (hydrochloric acid) from the parietal cells in the stomach lining, which is stimulated by factors such as the presence of food, the hormone gastrin, and the nervous system. The pH is essential for activating digestive enzymes and facilitating the breakdown of food. Additionally, the stomach has mechanisms to protect itself from excessive acidity, such as mucus production and bicarbonate secretion.