Regulation of gastrointestinal function

The digestive tract contains three types of sensory receptors that are sensitive to chemical or mechanical changes within the system. These include  

Receptor stimulation may lead to activation of any or all of the following regulatory mechanisms within the tract  

Hormone Source Stimulus for Release Hormone actions 

Gastrin G cells in pyloric region of the stomach Protein in stomach vagal stimulation Stimulates parietal cells (HC1) and chief cells (pepsinogen) in stomach enhances gastric motility 

Secretin Endocrine cells in mucosa of duodenum Acid in duodenum Inhibits gastric emptying and gastric secretion stimulates secretion of bicarbonate from pancreas stimulates secretion of bicarbonate-rich bile from liver 

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Experiments carried out in the conscious rat demonstrated that H3 receptors contribute only to the central, and not the peripheral, regulation of intestinal motility (Fargeas et al., 1989). In addition, the concomitant ineffectiveness on acid secretion of peripherally administered H3 ligands seems to exclude a significant role of H3 receptors in the peripheral regulation of gastrointestinal functions. Lastly, in the mouse H3 receptors do not seem to have any appreaciable influence on gastrointestinal motility (Oishi et al., 1993)... 

Role of lipase in the regulation of gastrointestinal function in humans. Am. J. Physiol. 273, G612-G620. 

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