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?