Gastric digestion of protein through pancreozyme action optimizes intestinal forms for absorption, mucin formation and villus integrity

The upper villus has first access to absorbed products where goblet cells assure continuance of mucin and continuity of the unstirred water layer. Glutamine is their dominant nutrient for synthesis of mucin oligosaccharides while also providing glutamic acid for either formation of its associated protein or is consumed for energy. Dietary cystine and threonine are frequently limiting, and their assurance is necessary for the mucin core while ready availability of glycine and/or serine together with proline also foster mucin formation. Unused absorbed products descend the villus in venules adjacent to the surface and provide nutrition as well as information about the lumen for adaptation of replacement cells. Sustaining the villus with absorbed nutrients takes priority for continuation of operational efficiency before their entry into the portal system and subsequent body use.