7 Pancreas secretions Flashcards
What is the duct hierarchy?
intercalated ducts
intralobular ducts
interlobular ducts
main duct
What is the ampulla of Vater?
the union of the pancreatic and common bile ducts
What types of cells are within pancreatic lobules?
acinar cells
What do acinar cells contain which is of significance here?
zymogen granules
What do duct epithelial cells do?
dilute secretions and ad bicarbonate to the secretions
What is the pancreatic acinar cell stimulated by, and what cell signalling pathway do they use?
CCK receptors
muscarinic ACHR’s
(PLC/Ca pathway)
Other than proteins, what does the acinar cell secrete, and how?
NaCl fluid secretion, to hydrate protein secretions
increase in intacellular Ca causes apical Cl channels to open, ultimately causing NaCl secretion
What adverse effect might acinar cells have on the ducts?
block them, leading to pancreatitis
Why would duct cells secrete bicarbonate?
to neutralise stomach acid and protect the small bowel
also, enzymes of the small bowel work at a neutral pH
What stimulates bicarbonate secretion by pancreatic duct cells?
ACH stimulates acinar cells which in turn stimulate duct cells
secretin
Where does the bicarbonate come from?
the blood, from alkaline tide of the stomach, but now the bicarbonate ions are coming in.
What do duct cells need to trasnport bicarbonate ions, where do we get it?
chloride ions
CTFR channel
What initiates secretin stimulation of duct cells?
duodenal acidification, secretin released by S cells
Where is CCK produced and in response to what?
I cells
in response to fatty meals or CCK releasing factors (like Luminal CCK releasing factor)
What does CCk stimulate?
protein secretion in acinar cells
What is Octeotride acetate used for?
it’s a somatostatin analogue, inhibiting CCK and secretin release.
What are the phases of pancreatic secretion?
cephalic
gastric
intestinal
What is the involvement of ACh and CCK in the cephalic phase?
ACh sitmulates Acinar cells
CCK not involved
What happens in the gastric phase?
release of Gastrin from G cells in the antrum , which is a weak agonist for CCK receptors.
What are the 3 major mechanisms for the intestinal phase?
gastric acid stimulates duodenal S cells to release secretin
lipids stimulate duodenal I cells to release CCK
Lipids also activate a vagovagal enteropancreatic reflex
What activates zymogens?
enteropeptidases, converting trypsinogen to trypsin (autocatalysis)
