Gastric juices are secreted from glands lining the stomach and function to break down food in the stomach and kill bacteria, according to the resource website About.com. Gastric juice is a general term that includes the fluid secreted from the cardiac, oxyntic and pyloric glands, all of which secrete distinctly different fluids. Combined in the stomach, gastric juice is made up of water, electrolytes, mucus, enzymes, hydrochloric acid and intrinsic factor.
According to About.com, each component of gastric juices works in its own way to break apart the various nutrients in the food consumed to allow them to be available for the body. While some components of gastric juices work on breaking down protein structures, others are adept at breaking down short- to medium-chain fats. An additional component present in gastric juices, amylase, is in the saliva and travels into the stomach to help break down carbohydrates.
About.com notes that the intrinsic factor in gastric juices allows the body to absorb B-12, a necessary nutrient for nervous system function and the production of blood cells. Once the gastric juices break down the food in the stomach, this nutrient is passed into the small intestine for further digestion and absorption to occur.