Gastric Secretion Flashcards
Name the 6 cell types involved in gastric secretion
parietal (oxyntic) cells chief cells mucous cells endocrine cells mast cells epithelial cells
What do parietal cells secrete?
H+
intrinsic factor
What do chief cells secrete?
pepsinogen
What do mucous cells secrete?
sulfated glycoproteins
What do endocrine cells secrete?
gastrin
What do mast cells secrete?
histamine
What do epithelial cells secrete?
HCO3-
prostanoids
Name the 5 functions of gastric secretion
protein digestion - acid and pepsin
inactivation of bacteria, viruses, and parasites
iron absorption - Fe2+ + H+ = Fe3+
intrinsic factor - vitamin B12 absorption
prostanoids - mucosal barrier cyto-protection
Name the 4 phases of gastric secretion
basal phase
cephalic phase
gastric phase
intestinal phase
Basal phase
that which occurs in the absence of all cephalic, gastric, and intestinal stimulation
Cephalic phase
that mediated by sight, smell, taste, swallowing
Gastric phase
that mediated by gastric distension and protein concentration
Intestinal phase
that mediated by duodenal amino acid concentration
Explain the cephalic phase of gastric secretion
vagal nerve stimulates parietal cells via Ach to secrete H+
vagal nerve stimulates G cells via Ach to release gastrin, which stimulates parietal cells to release H+
Explain the gastric phase of gastric secretion
distension stimulates G cells to produce gastrin, which stimulates parietal cells to release H+
amino acids and peptides from the food stimulates parietal cells to produce H+
distension also stimulates parietal cells to produce H+