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| align="center" colspan="2" |
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| colspan="2" bgcolor="#dddddd" | Identifiers
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| bgcolor="#e7dcc3" | Symbol(s)
| bgcolor="#eeeeee" | [SCT]
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| bgcolor="#e7dcc3" | Entrez
| bgcolor="#eeeeee" | [6343]
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| bgcolor="#e7dcc3" | OMIM
| bgcolor="#eeeeee" | [182099]
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| bgcolor="#e7dcc3" | RefSeq
| bgcolor="#eeeeee" | [NM_021920]
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| bgcolor="#e7dcc3" | UniProt
| bgcolor="#eeeeee" | [P09683]
|- class="hiddenStructure"
| bgcolor="#e7dcc3" | PDB
| bgcolor="#eeeeee" | []
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| colspan="2" bgcolor="#dddddd" | Other data
|- class="hiddenStructure"
| bgcolor="#e7dcc3" | EC number
| bgcolor="#eeeeee" | []
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| bgcolor="#e7dcc3" | Locus
| bgcolor="#eeeeee" | Chr. 11[p15.5]
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Secretin is a peptide hormone produced in the S cells of the duodenum in the Crypts of Lieberkuhn. Its overall effects is to regulate the pH of the duodenal contents via the control of gastric acid secretion and buffering with bicarbonate.
It is secreted in response to low duodenal pH due to acidic chyme.
It stimulates the secretion of bicarbonate from the liver, pancreas, and duodenal Brunner's glands in order to buffer the incoming protons of the acidic chyme. It also enhances the effects of cholecystokinin. It is known to promote the normal growth and maintenance of the pancreas.
It also reduces acid secretion from the stomach by inhibiting gastrin release from G cells. This helps neutralize the pH of the digestive products entering the duodenum from the stomach, as enzymes from the pancreas (eg, pancreatic amylase and pancreatic lipase) function optimally at neutral pH.
Secretin was the first substance which was identified to cause a physiological effect in the body after being transported via the blood. The term hormone was coined by Bayliss and Starling to categorise such chemical messengers.
