What is inside stomach?

The stomach is divided into four regions. They are the fundus, body, antrum and pylorus.

Within the stomach, but particularly in the small intestine, the surface area of the mucosa is greatly increased. The mucosal and submucosal layer is folded into microscopic villi on the surface of larger folds or ridges.

Intestinal villi are leaf-like or finger-like mucosal projections that lend a velvety appearance to the mucosa of the small intestine. On their surface, the villi are covered by absorptive epithelial cells known as enterocytes.

At the bases of the villi are the “crypts” where new epithelial cells are formed that migrate upward to the villi. These cells are sloughed off at a fairly rapid rate: the lifespan of villus cells in the small intestine is as little as 2 - 3 days (in man), that of colonic cells 3 – 8 days).

In general, the crypts are primarily involved in cell renewal, ion and water secretion, whereas the villus epithelium functions in nutrient acquisition.

The crypts of Lieberkuhn are interspersed among the villi. It is multi-potent stem cells that give rise to a series of committed progenitors, which subsequently undergo differentiation to defined cell types in each location.

The crypts are sub-epithelial tubular glands that secret intestinal juice for regionally varying composition.

Glandular cells are important in signaling the initiation and coordination of digestive processes, involving a large number of hormones neurotransmitters and paracrine factors.

As the enterocytes mature and migrate to the villus tip, they alter the type and distribution of membrane transporters and change from being secretory cells to absorbing cells.
What is inside stomach? 

The digestion of fat in human body

While a small amount of fat splitting may take place in the stomach, most of the digestion of food fat is carried on in the intestine through the action of intestinal and pancreatic enzyme and of bile.

In human body fat occurs mainly as neutral fat in the form of triglycerides of oleic, palmitic and stearic acid. In addition to neutral fats, fats include phospholipids, cholesterol and its ester. Neutral fats are triglycerides i.e, glycerol combined with three molecules of fatty acids.

The first step of fat digestion begins in the stomach. Lingual lipase secreted from the serous glands of the tongue, and gastric lipase, secreted from the chief cells of the gastric mucosa, digest approximately one third of the dietary triglycerides.

Main digestion of fats is carried out by pancreatic lipase at optimum pH 8 and temperature of 40° C.

Bile salts are helpful and break up the fat droplets, which are emulsified. This emulsification results in increase of the fat surface on which pancreatic lipase can act.

The main path of fat digestion progresses from triglycerides to 1,2-diglycerides, to 2-monoglycerides and finally to free fatty acids and glycerol, perhaps after isomerization to the 1-monoglyceride.

During digestion, exchange of free fatty acids with glyceride fatty acids occurs.

Fats are involved in brain development, inflammatory processes, atherosclerosis, carcinogenesis, aging and cell renewal.
The digestion of fat in human body