IMMUNOLOGY

Detailed explanation-1: -Stomach acid is a chemical barrier against infection. It is hydrochloric acid and is strong enough to kill any pathogens that have been caught in mucus in the airways or consumed in food or water.

Detailed explanation-2: -In the stomach several mucosal defence mechanisms protect the stomach against hydrochloric acid and noxious agents. The pre-epithelial protection is made up by the mucus-bicarbonate barrier. Mucus and bicarbonate, secreted by mucus cells, create a pH gradient maintaining the epithelial cell surface at near neutral pH.

Detailed explanation-3: -Your stomach lining also secretes hydrochloric acid, which creates the ideal conditions for the protein-digesting enzymes to work. The potent hydrochloric acid kills bacteria, protecting your body from harmful microbes which can enter your body in food.

Detailed explanation-4: -Gastric acid secretion is stimulated primarily by histamine released from enterochromaffin-like cells in response to gastrin (17). Gastric juice consists of HCl and pepsin and can kill bacteria within 15 min when the pH is less than 3.0 (8). If the pH is raised above 4.0, bacterial overgrowth may occur.

Detailed explanation-5: -The stomach is protected from self-digestion by the mucosal barrier. This barrier has several components. First, the stomach wall is covered by a thick coating of bicarbonate-rich mucus. This mucus forms a physical barrier, and its bicarbonate ions neutralize acid.

Detailed explanation-6: -The pH of gastric acid in humans is 1.5-2.0. According to a report summarized by Beasley et al[6], the pH level is much lower than that of most animals, including anthropoids (≥ 3.0), and very close to that of carrion-eating animals called scavengers, such as falconine birds and vultures[6].