The pancreas Flashcards
describe the pancreatic development?
The dorsal and ventral buds arise from the foregut-midgut
junction with the ventral bud being part of the Hepatobiliary
bud
- The duodenum rotates into a c-shape and the ventral bud
swings round adjacent to the dorsal bud and buds fuse. - ventral bud duct then becomes the main pancreatic duct
-
what is the pancreas split into?
uncinate, head, neck, body, tail.
where is the islet tissue most abundant?
in the tail
the tail then extends to the hilum of the spleen
what is the pancreas supplied by?
coeliac and superior
mesenteric arteries.
define endocrine
define exocrine
Endocrine = secretion into blood stream, distant effect (2%)
Exocrine = secretion into duct, local effect [98%].(pancreatic juices)
what does pancreatic disease involve?
exocrine AND endocrine effects
what are the endocrine pancreatic cells?
- derived from duct system
- become islets
- differentiate into alpha, beta, delta cells
alpha : glucagon
beta : insulin
delta: somatostatin
what are the exocrine pancreatic cells?
- Arranged in ducts.
- Acini are grape-like clusters
of secretory units - they secrete pro enzymes into ducts
PANCREATIC JUICE
what are the two components of the exocrine cells?
- acinar cells :LOW volume, VISCOUS,
enzyme-RICH - Duct and Centroacinar cells
– HIGH
volume, WATERY, HCO3 - RICH.
what are the functions of pancreatic juice?
- Neutralise acidic chyme from stomach
- Prevents damage to duodenal mucosa.
- Raises pH so pancreatic enzymes can function.
- Wash low volume enzyme secretion out of pancreas.
how does the rate of bicarbonate secretion change?
when the PH of the duodenum decreased the rate of bicarbonate increases
why does it stop when PH is still acidic at PH 5?
Bicarbonate secretion ODDLY plateaus when pH is still acidic but
this is OK as: bicarbonate bile helps neutralise AND Brunner’s
glands found in sub-mucosa secrete alkaline still.
what is the mechanism of bicarbonate secretion?
what antiporters are involved?
- Sodium moves down gradient via paracellular ‘tight’ junctions
- Water is drawn into the lumen by sodium raising lumen osmolarity.
Na+/H+ antiporter = secondary active transport
Cl-/HCO3
-antiporter = secondary active transport
‘Leak channels’ exist to allow chloride and potassium ions to
return back into the cell and blood respectively.
- This enables the pumping of bicarbonate to continue
where are enzymes secreted in the acinar cells stored?
examples?
stored in zymogen granules
e.g lipases, proteases and amylases.
what prevents the organ from auto digestion?
Proteases are released as inactive pro-enzymes (zymogens) which protects
the organ from auto-digestion
