Human Digestive System

Any food that contains fat causes the gallbladder to release bile. The higher the fat content of the food or meal, the more bile is released.

The mucous amembrane of intestinal wall is a single layered eptithelium of tall columber cells with interspersed golbelt cells. Thee epithelial cells have microvilli. In between the villi the mucous membrane is profusely folded and the infolding form pit-like simple tubular intestinal glands or crypts of Leiberkuhn. These secrete the intestinal digestive juice called succus entericus. Rennin is component of gastric juice secreted from stomach. It secreted in form of inactive proenzyme called prorennin. It changes the soluble casein proein of milk into insoluble semifluid calcium paracaseinate.Saliva is secreted from salivary glands. The saliva contain ptyalin (salivary amylase) in mammals. 

Lysozyme is an antibacterial enzyme present in phagocytic cells, tears, saliva, sweat and other body secretions. It digest peptidoglycan in bacterial cell wall. 

In a person, addict for alcohol a part of alcohol is changed to acetaldehyde. Hangover is due to it. Acetaldehyde stimulates formation of fat which is deposited over the wall of arteries and in the cells of liver . With the accumulation of fat the liver cell fail to produce protein and enzymes. There is little regulation of fat, protein and carbohydrate metabolism. This disorder is called fatty liver syndrome. Liver later turns into a fibrous organ. 

Bile is secreted by liver and is stored in the gall bladder. In human bile there are two salts sodium taurocholate and sodium glycocholate. Emulsification of fat takes place through tehse bile salts, therefore, the amount of bile will release in proportion to the amount of fat in meal. 

The water and many dissolved substances form the blood are filtered into the lumen of the bowman's capsule. The glomerular filtrate contains a large amount of water and other substances. Thus, glomerular filtrate and blood plasma are similar except that glomerular filtrate does not have protein and fats. 

Assimilation is the process by which absorbed nutrients are incorporated into the cells of an organism to be used for energy, growth, and repair. Digestion is the breakdown, and absorption is the uptake into the blood.

Digestion is the biological process of breaking down large, complex, insoluble food molecules into smaller, simpler, water-soluble molecules that can be absorbed by the body.

Absorption is the process by which the products of digestion are absorbed into the blood or lymph through the intestinal wall.

Egestion is the process of discharging undigested or waste material from the body.

Pinocytosis, otherwise known as cell drinking fluid endocytosis, and bulk-phase pinocytosis, is a mode of endocytosis in which small particles are brought into the cell, forming an invagination, and then suspended within small vesicles.

Gastrin is secreted by stomach cells. Parathormone is secreted by parathyroid gland, thyroxin by thyroid gland and insulin by pancreas.

The enzyme liberated by platelet is thromboplastin. It helps in blood coagulation.

Rumen of a cow is a part of its stomach. It serves as the primary site for microbial fermentation of ingested feed.