https://wiki.tiffa.net/w/index.php?action=history&feed=atom&title=Translations%3AVitamin_B12%2F67%2Fen 2026-09-11T14:18:19Z Revision history for this page on the wiki MediaWiki 1.43.0 https://wiki.tiffa.net/w/index.php?title=Translations:Vitamin_B12/67/en&diff=135261&oldid=prev 2024-04-05T11:15:36Z

<p>Importing a new version from external source</p> <p><b>New page</b></p><div>==Physiology==<br /> ===Absorption===<br /> Vitamin B&lt;sub&gt;12&lt;/sub&gt; is absorbed by a B&lt;sub&gt;12&lt;/sub&gt;-specific transport proteins or via passive diffusion. Transport-mediated absorption and tissue delivery is a complex process involving three transport proteins: [[haptocorrin]] (HC), [[intrinsic factor]] (IF) and [[transcobalamin II]] (TC2), and respective membrane receptor proteins. HC is present in saliva. As vitamin-containing food is digested by [[hydrochloric acid]] and [[pepsin]] secreted into the stomach, HC binds the vitamin and protected it from acidic degradation. Upon leaving the stomach the hydrochloric acid of the [[chyme]] is neutralized in the [[duodenum]] by [[sodium bicarbonate|bicarbonate]], and pancreatic proteases release the vitamin from HC, making it available to be bound by IF, which is a protein secreted by gastric [[parietal cell]]s in response to the presence of food in the stomach. IF delivers the vitamin to receptor proteins [[cubilin]] and [[amnionless]], which together form the [[cubam]] receptor in the distal [[ileum]]. The receptor is specific to the IF-B&lt;sub&gt;12&lt;/sub&gt; complex, and so will not bind to any vitamin content that is not bound to IF.</div>

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