胃液、胰液、胆汁的主要成分和作用（The main component and function of gastric juice, pancreatic juice, bile）.docVIP

胃液、胰液、胆汁的主要成分和作用（The main component and function of gastric juice, pancreatic juice, bile） The main component and function of gastric juice, pancreatic juice, bile (1) the main components of gastric juice include: HCl, pepsin, mucin, endogenous factors and so on. 1) the role of hydrochloric acid Hydrochloric acid is secreted by secreting glandular cells: it can kill bacteria entering the stomach with food, so it is important for maintaining the sterile state of the stomach and small intestine. Activating pepsin, transforming it into active pepsin, and providing the necessary acidic environment for pepsin action. After the hydrochloric acid into the small intestine can cause secretin release, thereby promoting the secretion of pancreatic juice, bile and intestinal fluid. The acidic environment caused by hydrochloric acid is also helpful for the absorption of iron and calcium in the small intestine. 2) the role of pepsinogen Pepsin is synthesized and secreted by main cells, whose main function is to break down proteins. The major products are long chain peptides, oligo peptides and small amounts of amino acids. Pepsin can only function in acidic environment, and its optimum pH is 2. With the increase of pH, the activity of pepsin decreased, and irreversible degeneration occurred when pH rose above 6. 3) the major role of mucus and bicarbonate Mucus and bicarbonate together form a mucous - bicarbonate barrier that protects against gastric acid and pepsin and acts as a protective barrier to the gastric mucosa. 4) the main role of internal factors The inner factor (intrinsic factor glycoprotein, secreted from gastric mucosa and the molecular weight is about 50 thousand) and dietary vitamin B12 (external factor, extrinsic factor) combined to form a compound, the compound has a strong resistance to proteolytic enzymes, vitamin B12 can protect the intestinal damage by hydrolase. When the complex moves to the ileum, it can be combined with a specific receptor in the distal i