My textbook says, secretin secretion is triggered by the presence of acidic chyme in intestine.

But why is secretin sensitive to acidic environment? I checked the wikipedia page of secretin and found no related information. Is there some mechanism for secretin to secrete in presence of acidic chyme?


The exact mechanism by which secretin is released is still not known.

The mechanism by which acid brings about secretin release is not fully understood but probably involves acid sensing ion channels of the Trp family present in the brush border of S-cells.

Physiological reason for susceptibility to acid: It is because this hormone acts on pancreas and increases the secretion of bicarbonates to increase the pH. It also reduces gastric motility thereby allowing longer digestion within the stomach. So, it effectively prevents deterioration of duodenal mucosa and helps in efficient absorption of lipids by increasing ph in duodenum which is required for better action of lipases. So, its secretion is induced by increased acidity from chyme (so that it can increase pH).

Thus, we can conclude that secretin is acid sensitive.

Source: https://www.pancreapedia.org/molecules/secretin

  • 2
    $\begingroup$ You forgot to connect your last paragraph to "thus it is acid-sensitive" (its not easy to draw this conclusion from your paragraph). Anyways, +1! ;) $\endgroup$ Apr 16 '17 at 15:55

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