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[6] [7] [8] VIP stimulates contractility in the heart, causes vasodilation, increases glycogenolysis, lowers arterial blood pressure and relaxes the smooth muscle of trachea, stomach and gallbladder. In humans, the vasoactive intestinal peptide is encoded by the VIP gene. [9] VIP has a half-life (t ½) in the blood of about two minutes. [10]
The intestinal epithelium is the single cell layer that forms the luminal surface (lining) of both the small and large intestine (colon) of the gastrointestinal tract. Composed of simple columnar epithelium its main functions are absorption, and secretion. Useful substances are absorbed into the body, and the entry of harmful substances is ...
Mucus forms a layer (or layers, in the case of the colon) that separates the bulk of the luminal contents from the intestinal epithelium. The mucus consists of a highly glycosylated hydrated gel formed by mucin molecules that are secreted by goblet cells. The mucus prevents large particles from contacting the epithelial cell layer while ...
This fluid is composed of four primary components: ions, digestive enzymes, mucus, and bile. About half of these fluids are secreted by the salivary glands, pancreas, and liver, which compose the accessory organs and glands of the digestive system. The rest of the fluid is secreted by the GI epithelial cells.
Mucus is made up of a fluid component of around 95% water, the mucin secretions from the goblet cells, and the submucosal glands (2–3% glycoproteins), proteoglycans (0.1–0.5%), lipids (0.3–0.5%), proteins, and DNA. [7] The major mucins secreted – MUC5AC and MUC5B - are large polymers that give the mucus its rheologic or viscoelastic ...
Intestinal glands are found in the epithelia of the small intestine, namely the duodenum, jejunum, and ileum, and in the large intestine (colon), where they are sometimes called colonic crypts. Intestinal glands of the small intestine contain a base of replicating stem cells , Paneth cells of the innate immune system , and goblet cells , which ...
The pH level of the mucus also plays a role in its viscosity, as higher pH levels tend to alter the thickness of the mucus, making it less viscous. [1] Because of this, invading agents such as Helicobacter pylori, a bacterium that causes stomach ulcers, can alter the pH of the mucus to make the mucus pliable enough to move through. [3]
Goblet cells are simple columnar epithelial cells, having a height of four times that of their width. The cytoplasm of goblet cells tends to be displaced toward the basal end of the cell body by the large mucin granules, which accumulate near the apical surface of the cell along the Golgi apparatus, which lies between the granules and the nucleus.