PHGY 210 Lecture Notes - Lecture 29: Trypsin Inhibitor, Histamine Receptor, Mucin
Mar 20, 2017
Summary of Lecture #6
Gastric Glands in Fundus and Corpus
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Mechanism of Acid Secretion
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-proton pump is location of ulcer treatment b/c it’s unique to this area
Parietal Cell Secretion
-pure HCl fluid
-constant composition, pH ~ 0.8
-independent of type, magnitude of stimulus
Mixed Gastric Juice
-pH ~ 1-2
-modified by non-parietal alkaline gastric secretions
-pH of mixed gastric juice depends on number of parietal cells that are active
Functions of HCl
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Document Summary
Proton pump is location of ulcer treatment b/c it"s unique to this area. Ph of mixed gastric juice depends on number of parietal cells that are active. Mucin secretion: all surface epithelial cells, cardiac and pyloric tubular glands, mucous neck cells (fundus and corpus) Secretagogues = amino acids or partially digested proteins which act on gastrin-releasing cells. Gastrin (peptide hormone) released by endocrine cells in antrum (g-cells) in response to: secretagogues (products of protein digestion, local enteric reflexes (distention in antrum, vagally-mediated reflexes. Physiological role of gastrin: stimulates hcl secretion, trophic effect. Histamine administration elicits large volume of gastric juice w/ lots of hcl. Histamine receptor is different than the allergy ones. Histamine is constantly released and presented to parietal cells as tonic background, sensitizing them to other stimuli. Blocking this tonic/background release of histamine or using h2-receptor antagonists, inhibits acid secretion in response to ach and gastrin. H2-receptor blockers are widely used to decrease hcl secretion.
