Gastric acid
Stomach acid is, as the name suggests, an acid (more precisely hydrochloric acid) with an extremely low pH value, which serves the digestion of the food taken in and the first defence against pathogens taken in with the food. Alternatively, the word “gastric juice” is also used. The consistency is mucilaginous, because in addition to the acid, mucus is also formed by various stomach cells to protect the stomach lining from self-digestion and a protein-splitting enzyme called pepsin.
The gastric juice also contains a transport molecule, the so-called intrinsic factor, which is essential for the absorption of vitamin B12 in the small intestine. Among other things, vitamin B12 has an important function in blood formation. The mere sight or smell of food leads to the secretion of gastric juice. A further secretion occurs after and during food intake by stretching the stomach.
Saliva
Saliva is a bodily fluid produced by the salivary glands that serves to predigest the food taken in and to moisten it. The moistening leads to the gliding of the food and facilitates the passage of the esophagus. The enzymes contained in saliva break down multi-chain sugar molecules, such as starch, which are mainly contained in food, and thus facilitate further digestion. In addition, antibodies that enter the oral cavity with the saliva prevent infection by neutralizing possible pathogens.
Bile
The bile is a bodily fluid that is produced in the liver and released into the small intestine via the bile ducts. The gallbladder serves to store and quickly mobilize bile, but is not essential for survival. In the small intestine, the greenish body fluid is used for digestion and absorption of fats.
For this reason, bile is secreted mainly during and after eating. Furthermore, metabolic products are dissolved in the bile, which are excreted with the stool after it has been expelled. These include bilirubin, which is produced when the red blood pigment is broken down and gives the stool its brownish color. The body also frees itself from absorbed heavy metals by excreting them with the help of bile. The acids contained in the bile also kill bacteria and protect the body from infections.
