Secretin

Secretin is a hormone produced in the S cells of the duodenum in response to low duodenum pH and fatty acids in the duodenum to stimulate the secretion of bicarbonate from bicarbonate producing organs(liver, pancreas, Brunner's glands) when the pH drops below a set value. This helps neutralize the gastric acid entering the duodenum from the stomach.

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It also inhibits acid secretion from the stomach by reducing gastrin release from the G cells of the stomach.

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It contains 27 amino acids and is homologus to glucagon.

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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.

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Hormone: A hormone (from Greek horman - "to set in motion") is a chemical messenger from one cell (or group of cells) to another. All multicellular organisms produce hormones (including plants - see article phytohormone)....

S cell: S cells are cells which release secretin, found in the jejunum and duodenum. They are stimulated by a drop in pH in the small intestine's lumen. The released secretin will increase the secretion of HCO3- into the lumen....

Duodenum: In anatomy of the digestive system, the duodenum is a hollow jointed tube that connects the stomach to the jejunum. It is the first part of the small intestine, and is about 18 cm (7 in) long. It starts with the duodenal bulb and ends at the ligament of Treitz. Two very important ducts open into the...

Secretin related Images and Photos (experimental)

The Secret in Their Eyes