Why is stomach acid strong?
In order to kill any bacteria present on the food eaten by the animal.
Why does the strong acid in the stomach not dissolve the organs in the digestive system including the stomach?
Stomach acid or gastric acid is a strong acid. Gastric acid is secretion produced in the stomach. It is one of the main ditotonic soloutions secreted, together with several enzymes and intrinsic factors. Chemically it is an acid solution with a pH of 1 to 2 in the stomach lumen, consisting mainly of hydrochloric acid (HCl) (around 0.5%, or 5000 parts per million), and large quantities of potassium chloride (KCl) and sodium chloride (NaCl).
H. pylori live in the mucous lining of the stomach. Safe inside there, they are able to fight the stomach acid that does reach it with urease it releases. Urease converts the urea in the stomach into bicarbonate and ammonia, which are strong bases. This creates a cloud of acid-neutralizing chemicals around the H. pylori, protecting it from stomach acid.