GI Hormones Flashcards
Where are gut endocrine cells found? Germ layer derivation?
Crypts in the GI tract epithelium
Endodermal
What pole do gut endocrine cells secrete hormones?
Basal
Gut endocrine cells are distinguished by not having microvilli true or false?
False - they do have microvilli, they are distinguished by being paler than other cells
Gut hormones are what type?
Peptide
Which cells secrete histamine in the gut?
Enterochromaffin-like cells
Actions of histamine in the gut?
Stimulate gastric acid (HCl) secretion via H2 receptors on oxyntic cells
What causes histamine release by ECL cells?
Vagal stimulation, stretch or gastrin
Actions of gastrin (+ broad mechanism)
Gq coupled — PKC induces insertion of K/H ATP-ase into apical membrane of oxynitic cells
— gastric acid secretion (HCl)
Pepsin secretion
What cells release gastrin?
G cells
Stimulation of gastrin release from G cells?
What inhibits gastrin release?
Stimulates:
Amino acids
Vagus stimulation
Distension of stomach
Hypercalcaemia
Inhibits:
Low pH (negative feedback) Somatostatin
Which cells secrete secretin?
S cells
Where are S cells found?
Duodenum to ileum
What stimulates secretin release? Inhibits?
Acid in proximal duodenal lumen
Somatostatin
What are the actions of secretin?
Gs coupled PKA activates CFTR and Cl/HCO3 exchanger
Stimulates pancreatic and liver HCO3- secretion and water
Which cells secrete CCK and where are they located?
I cells in duodenum and jejunum
