Answer
The classical GI hormones are secreted by epithelial cells lining the lumen of the stomach and small intestine. These hormone-secreting cells - endocrinocytes - are interspersed among a much larger number of epithelial cells that secrete their products into the lumen or take up nutrients from the lumen. GI hormones are secreted into the blood, and hence circulate systemically, where they affect the function of other parts of the digestive tube, liver, pancreas, brain, and a variety of other targets.
Work Step by Step
The classical GI hormones are secreted by epithelial cells lining the lumen of the stomach and small intestine. These hormone-secreting cells - endocrinocytes - are interspersed among a much larger number of epithelial cells that secrete their products into the lumen or take up nutrients from the lumen. GI hormones are secreted into the blood, and hence circulate systemically, where they affect the function of other parts of the digestive tube, liver, pancreas, brain, and a variety of other targets.
There are a large number of hormones, neuropeptides, and neurotransmitters that affect gastrointestinal function. Interestingly, a number of the classical GI hormones are also synthesized in the brain, and sometimes referred to as "brain-gut peptides". The significance of this pattern of expression is not clear.
Hormone :
1. Gastrin stimulates gastric acid secretion and proliferation of the gastric epithelium
2. Cholecystokinin stimulates the secretion of pancreatic enzymes, and contraction and emptying of the gall bladder
3. Secretin stimulates the secretion of water and bicarbonate from the pancreas and bile ducts
4. Ghrelin appears to be a strong stimulant for appetite and feeding; also a potent stimulator of growth hormone secretion.
5. Motilin apparently involved in stimulating housekeeping patterns of motility in the stomach and small intestine
6. Gastric Inhibitory Peptide inhibits gastric secretion and motility and potentiates the release of insulin from beta cells in response to elevated blood glucose concentration
