Editing Stomach (section)

=== Gastric peptides ===

** Gastrin
*** Produced by G cells in the       antrum
*** Similar in form and       function to CCK
*** Release stimulated by       gastric distension, gastrin-releasing peptide and protein digestion       products. Release inhibited by luminal acid.
*** Primary endocrine regulator       of the secretory phase of a protein meal
**** Stimulates        enterochromaffin-like (ECL) cells to synthesise and release histamine
**** Exerts direct action on        parietal cells to stimulate acid release
**** Trophic effects on        parietal cells and ECL cells
*** Hypergastrinaemia is most       commonly the result of acid-reducing treatment like PPIs
****
** Somatostatin
*** Produced by delta cells -       diffuse neuroendocrine cells located in fundus and antrum
*** Stimulated by antral       acidification and gastrin-releasing peptide, and inhibited by       acetylcholine (from vagal fibres)
*** Acts to inhibit parietal       cell acid secretion directly and also inhibits gastrin release from G       cells and downregulates histamine release from ECL cells
** Histamine
*** Histamine release is       stimulated by gastrin, VIP, ghrelin, achetylcholine, and adrenaline, via       their actions on ECL cells
*** Inhibited by somatostatin
*** Stimulates parietal cells       to release acid
** Ghrelin
*** Produced by enteroendocrine       cells of the oxyntic glands in GIT
*** Levels are highest before       meals during fasting and decrease after meals
*** Decreased levels have been       associated with gastritis, and are seen post-bypass or sleeve       gastrectomy (unknown mechanism)
*** Increases gastric emptying       and motility, and increases gastric acid secretion, in preparation for       digestion