- Secretin
Protein
Name=PAGENAME
caption=
Symbol=SCT
AltSymbols=
HGNCid=10607
Chromosome=11
Arm=p
Band=15
LocusSupplementaryData=.5
ECnumber=
OMIM=182099
EntrezGene=6343
RefSeq=NM_021920
UniProt=P09683
PDB=Secretin is a
peptide hormone produced in theS cell s of theduodenum in thecrypts of Lieberkühn . Its primary effect is to regulate thepH of the duodenal contents via the control ofgastric acid secretion and buffering withbicarbonate . It was the first hormone to be discovered (see below).Stimulus
Secretin is secreted in response to low duodenal pH due to
chyme , which containshydrochloric acid , entering from the stomach. It is the active form ofprosecretin .Function
Secretin stimulates the secretion of
bicarbonate (base) (bile) from theliver , watery bicarbonate solution from pancreatic duct epithelium, and duodenalBrunner's gland s in order to buffer the incomingprotons of the acidic chyme [Guyton, Hall. Textbook of Medical Physiology 11edt. Elsevier, 2006. pp 800-801] . It also enhances the effects ofcholecystokinin . It is known to promote the normal growth and maintenance of thepancreas .It counteracts
blood glucose concentration spikes by triggering increasedinsulin release, following oralglucose intake. [cite journal |author=Kraegen EW, Chisholm DJ, Young JD, Lazarus L |title=The gastrointestinal stimulus to insulin release. II. A dual action of secretin |journal=J. Clin. Invest. |volume=49 |issue=3 |pages=524–9 |year=1970 |pmid=5415678 |doi=10.1172/JCI106262 [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=322500 Free Full Text] ]It also reduces acid secretion from the
stomach by inhibitinggastrin release fromG cell s. This helps neutralize the pH of the digestive products entering the duodenum from the stomach, as digestiveenzyme s from the pancreas (eg,pancreatic amylase andpancreatic lipase ) function optimally at neutral pH.tructure
Secretin is a
peptide hormone , composed of 27amino acids , of which 14 amino acids arehomologous to the sequence ofglucagon .History
In 1902,
William Bayliss andErnest Starling were studying how the nervous system controls the process of digestion. It was known that the pancreas secreted digestive juices in response to the passage of food into the duodenum. They discovered (by cutting all the nerves to the pancreas in their experimental animals) that this process was not, in fact, governed by the nervous system. They determined that a substance secreted by the intestinal lining stimulates the pancreas after being transported via the bloodstream. They named this intestinal secretion "secretin". Secretin was the first such "chemical messenger" identified. This type of substance is now called a "hormone ", a term coined by Bayliss in 1905.References
ee also
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Secretin receptor External links
* [http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/gi/secretin.html Overview at colostate.edu]
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