Pancreas and Liver Flashcards
What are the functions of the exocrine liver and pancreas?
Provide excretions directly into digestive lumen to:
- digest carbs, proteins, lipids in the small intestine BEFORE ABSORPTION HAS TAKEN PLACE.
- neutralize acid remaining from stomach (using HCO3-)
What is the function of the endocrine liver and pancreas ?
Regular blood borne energy substrate availability via hormones AFTER ABSORPTION HAS TAKEN PLACE.
What are examples excretions the exocrine pancreas secretes ?
Pro-enzymes, HCO3- (helps neutralise acid)
How are the digestive secretions secreted into the small intestine ?
Via pancreatic duct to the 2nd part of the duodenum.
Where is the pancreas located ?
Retroperitoneal (part of abdomen behind peritoneal cavity), close to major blood vessels. Lies in C shaped curve of duodenum (except tail)
What are the different parts of the pancreas ?
Tail, Body, Head, Neck, Uncinate Process
What other structures does the pancreatic duct connect with ?
With the common bile duct, and the 3 components of the sphincter of Oddi
How is the pancreas supplied with blood ?
Mainly by
- the splenic artery (from coeliac trunk)
- the pancreatico-duodenal artery (from coeliac trunk or Superior Mesenteric Artery)
What are the main secretory cells of the exocrine pancreas ?
Acinar cells
What substances do these cells secrete ?
Enzymes, Na+, K+, Cl-, HCO3-, serous secretions
How are acinar cell clusters connected?
By intercalated ducts
Where do these intercalated ducts converge?
In collecting duct
Which substances do the ductal cells (the cells lining the duct) add to the secretion ?
Serous and HCO3- secretions
During which phase of digestion are most of the secretions of the exocrine pancreas produced ? How are the secretions controlled in that case ?
Intestinal phase (about 65%). Secretions are controlled hormonally by secretin (in response to acid) and CCK (in response to AAs, FAs, monoacylglycerols).
How are the secretions of the exocrine pancreas regulated during the cephalic phase ? And how much pancreatic secretions are produced?
About 25%
Vagus nerve is stimulates pancreatic secretions by releasing ACh and VIP
How are the secretions of the exocrine pancreas regulated during the gastric phase ? And how much pancreatic secretions are produced?
About 10%
Mediated by vagovegal reflex
What are zymogen granules ?
- Found in acinar cells
- House mainly inactive digestive enzymes
- Secreted by exocytosis from Acinar cells into luminal space upon activation
- Secretion occurs in response to CCK, VIP and Gastric-releasing peptide
How is exocytosis of zymogen granules (for release of enzymes) exactly regulated ?
Regulated hormonally and neurally.
-CCK is released into interstitial space —> enters bloodstream —-> travels to pancreatic acinar cells —–> binds to CCKA receptors —–> stimulation of acinar cells
-CCK is released into interstitial space —> enters bloodstream —-> travels to vagal afferent —–> binds to CCKA receptors —–> gives efferent stimulation of acinar cells via VIP