Human Digestive System

Grazing is a method of feeding in which an animal feeds on plants such as grasses. The animals are called grazing animals. They are also called as Ruminants. Examples include cattle, sheep, goats, deer. They are capable of digesting cellulose present in the plants. The cellulose is digested by intestinal bacteria present in them. These bacteria possess the necessary enzymes to digest cellulose in the GI tract.

All the constituents of food are digested but roughage or fibres are not digested, but they play a very important role in the formation and smooth elimination of bowels.

Enterogastrone is a hormone secreted by the duodenal mucosa that inhibits gastric secretion and motility when fat is present in the duodenum.

Pepsin enzymes are the enzymes that help in degradation of the proteins into various components like peptones. These enzymes are mostly found in stomach which has acidic pH.

Rennin (chymosin) is an enzyme that helps in the digestion of milk proteins. It is found in the gastric juice of young mammals (like calves) and human infants to digest milk, but its production decreases significantly in human adults.

Rennin is an enzyme primarily found in the gastric juice of infant mammals to coagulate milk. In adult humans, rennin is typically absent or present in negligible amounts.

Rennin is the specific gastric enzyme in infant mammals that converts soluble caseinogen into insoluble casein, which is then digested by pepsin.

Zymogen cells, also known as chief cells or peptic cells, are located in the gastric glands and are responsible for secreting pepsinogen, the inactive precursor to pepsin.

Pepsin is a protease that requires a low pH environment, provided by hydrochloric acid in the stomach, to become active and function optimally.

Gastric acid secretion is stimulated by multiple pathways: gastrin (hormonal), histamine (paracrine), and vagal activation (neural). Therefore, all these factors contribute to the process.

Chief cells (or zymogen cells) are the primary source of pepsinogen secretion in the gastric glands of the stomach.

Liquids, especially those like beer or water, pass through the stomach much faster than solid foods like proteins, carbohydrates, or fats, which require significant mechanical and chemical breakdown.

Pepsin is produced as the inactive zymogen pepsinogen by the zymogen (chief) cells of the stomach lining.

Pepsinogen is an inactive proenzyme. It is converted into the active enzyme pepsin by the acidic environment created by hydrochloric acid (HCl) in the stomach.