gastroenterology - pancreas and small bowel Flashcards
What are first 2 steps of pancreatic embryology?
What happens in 3rd step of pancreatic emrbryology?
What is the major pancreatic vessel? And what does it join up with?
major papilla
joins with distan commone bile duct to form papilla ampulla
Describe structure of pancrease?
head, neck, body, tail
Find the pancreas on this CT scan?
what type of imagery is this?
What is difference between endocrine and exocrine secretions?
endocrine - into blood stream, effect on distant target organ, ductless glands
exocrine - into duct have direct local effect?
Main endocrine secretions of pancreas?
insulin - anabolic
glucagon
somatostatin - endorcrine cyanide
Where is endocrine area of pancrease + how much of % of pancrease?
islets of langerhans
2
What is function of exocrine part of pancreas?
98%
secretess pancreatic juice into duodenum via sphincter of oddi/ampulla
digestive function
What are acinin?
ducts, grap like clusters of secretory units
acinar cells secrete pro enz into ducts
What are islets?
derived from brahncing duct
loose contact with ducts
differentiate into a and b cells secret into blood
more of them in tail than head
What is organisation of pancreatic microanatomy?
identify acinar and islets of langerhans
Label histologt of islet?
Label acini
What are 2 components of pancreatic juice
and which 2 cells produce each one?
How is bicarbaronate juice produces?
what is its function(2)?
What is relationship between dunodenal pH and bicarbonate secretions?
Why does HC03- secretions stop when pH is still acidic?
What is mechanism of HC03 secretion (think C02)?
What happens to HC03- produced in pancreatic duct cell?
How is excess Na+ in panreactic cell dealt with?
How are K+ and Cl- levels in pancreatic cell balanced out?
How is what happens in pancreatic cell similar to gastric parietal cells?
Where are enzymes for digestion stored and syntehied?
in zymogen granules in acinar cell
What is a zymogen?
pro enzyme
What preventes the enzymes from possbiel causing damage to pancreas (4)?
How are some proteoylic and soem lytic enzymes converted into active forms?
duodenal mucosa secrete enterkinase
What do lipases additionally need? (2)
some require colipase (precursor)
presence of bile salts for effective actions
what can lack of pancreatic enzymes cause?
can cause malnutrition even if diertay input is ok
side effects from orlistat ( inhibte lipases)?
increase faecal fat, steatohrea
what are 3 phases of pancreatic juice secretion?
cephalic
gastric
intestinal
What happens in cephalic?
reflex to sight good
causing enzyme rich compnent of acini only
low volume , mobilisation enz
what happens in gastric phase?
stimulation of pancreatic secretion of food in stomach
same mechanism sa cephalic
what happens in intestinal phase?
how is it mediated?
what is differnet about it?
hormnal mediated when gastric chyme enter duodenum
BOTH components of pancreatic huice are stimulated
HC03- AND enz flow in duodenum
How in enz secretion of acini controlled?
how is bicaronate secretion controlled in duct and centroacinar cells?
secretin (cAMP)
how exactly does CCK control enzyme secretions in acini?
CCK is controlled by duodenal I cell
CCK release is stimulated by fatty acid and Amino acid
CCK is inhbited by trypsin
What is important to consdier about acinar fluid?
It is isotonic - resembles plasma in its concs
secretions of acinar fluid and protients it contains is stimulated by CCK
What does the secretin cause?
secretions of H20 and HC03- from cells lining extralobular ducts
Why is secretin stimulation secretions richer in HC03- than acinar secretions?
Due to Cl- and HC03 exhcnage
how is HC03- controlled? (-ve feedback)
What is important about CCK effect on HC30-?
no effect alone
NEEDS stimulattion on secretin
What effect does vagus nerve have?
similar effect to CCK
What effect does secretin have on enzyme secretions?
NO EFFECT
What happens when you eat a meal?
starting with low pH stomach
to how pH is lowered
to enzyme release
