functions and secretions of the pancreas Flashcards
pancreas
soft retroperitoneal gland
sits behind stomach
12-15cm x 2.5cm
has head, body, tail
releases 1.5L juices a day - into duodenum
pancreatic duct carries secretions to ampulla of vater
bile from gall bladder enters there too
bile produced by liver + contains bile salts
where is the duodenum
at the start of the small intestine
at the start of the small intestine
opening in the duodenum
why are bile salts important
essential for fat absorption
what type of gland is the pancreas
endocrine + exocrine
function of the pancreas
exocrine + endocrine gland
function of pancreas - exocrine gland
produces pancreatic juice
99% of cell mass
acinar + duct cells
juices released into duodenum
breaks down all categories of foodstuff
function of pancreas - endocrine gland
produces hormones
1% of cell mass
islets of langerhans
hormones released into bloodstream
insulin, glucagon, somatostatin
what are the exocrine secretions of pancreas
digestive enzymes
alkaline juice
explain digestive enzymes - exocrine secretions
digests all food types
proteases
lipases
carbs
nucleases
what type of foods do digestive enzymes digest
proteases
lipases
carbs
nucleases
what do exocrine glands produce
pancreatic juice
what do endocrine glands produce
hormones
what are acinar cells specialised for
production + export of large quantities of digestive enzymes
what are acinar cells stimulated by + release as a result
primarily by CHOLECYSTOKININ (CCK) to release enzymes
what do acinar cells cause the gall bladder to do
contract + release bile
what does CCK inhibit
HCl secretion from the stomach
acinar cells surround ……. ….. …….
islet of langerhans
acinar cells - full explanation
- specialised for production and export of large quantities of digestive enzymes
- stimulated primarily by CHOLECYSTOKININ (CCK) to release enzymes
- causes the gallbladder to contract and release bile
- CCK also inhibits HCl secretion from the stomach
- secretin and ACh can also induce acinar cell enzyme release
what are duct cells specialised for
electrolytes
when is HCO3- released fro the pnacreas
after eating
duct cells - full explanation
- specialised for transport of electrolytes
- a HCO3- rich juice is released from the pancreas after eating but a Cl- rich juice is secreted when flow rates are low
- stimulated by secretin to release a HCO3- rich juice
- secretin also inhibits HCl secretion from the stomach
- ACh can also induce duct cell HCO3- release
classes of enzymes in pancreatic juice
- proteases = 90%
- amylase = 7%
- lipases = 2%
- nucleases = <1%
- composition of juice is predominantly proteases
what are the 3 phases of acid secretion
cephalic
gastric
intestinal
what is the ampulla of vater
muscular structure surrounding bile and pancreatic ducts as they enter the duodenal wall
what are the 2 type of exocrine secretions of the pancreas
digestive enzymes + alkaline juice
digestive enzymes - digestion explanation
digests all food types
proteases, lipases, carbs, nucleases
alkaline juice - digestion explanation
numerous functions
neutralises gastric acid
prevents ulcer formation
enables pancreatic enzymes to work
enables micelle formation
when is the plasma alkaline tide generated
when gastric parietal cells produced acid/H+ neutralised by pancreatic duct cells as they produce HCO3-
describe the alkaline tide
- stomach parietal cells send H+ (acid) into stomach and HCO3- into plasma
- HCO3- in plasma causes alkaline tide - plasma pH INCREASES
- when gastric acid arrives at duodenum, sensitive cells release secretin - signals pancreas to send HCO3- into duodenum + H+ into plasma
- pancreatic HCO3- entering duodenum neutralises acid/H+ arriving from stomach
- pancreatic H+ entering plasma neutralises alkaline tide/HCO3- arriving from stomach
gastrin
secreted by:
G-cells of stomach
targets:
gastric parietal + histamine secreting cells
releasing stimuli:
gastric distention + small peptides in stomach
actions:
stimulates gastric HCl secretion
secretin
secreted by:
endocrine cells of small intestine
targets:
stomach + pancreas
releasing stimuli:
acid in duodenum
actions:
inhibits gastric HCl secretion
stimulates pancreatic HCO3- secretion
CCK
secreted by:
endocrine cells of small intestine - duodenum
targets:
stomach - esp. muscle
pancreas
gallbladder
releasing stimuli:
fat in duodenum
actions:
inhibits gastric emptying - DECREASE MOTILITY
stimulated pancreatic enzyme secretion
induces gallbladder contraction
enzymes are secreted from the pancreas as ….. ….
inactive zymogens
only become activated when in the SI
why do enzymes only become activated when in the SI
to prevent autodigestion
when pancreatic trypsinogen enters the SI what is it converted itno
the active digestive protease trypsin by ENTEROKINASE
where is enterokinase found
in the brush border cells of the villi
- so activation only takes place in the SI
pancreatic enzymes
digestive enzymes secreted from the pancreas - inactive zymogens
only activated in the SI
prevents autodigestion of pancreas
when pancreatic trypsinogen - enters the SI
converted into active digestive proteases by enterokinase - found in the brush border cells of the villi
activation only takes place in the SI
trypsin can activate other inactive zymogens
oancreas has trypsin inhibitors - prevent autodigestion
how is trypsinogen converted into trypsin
enterokinase
trypsin
how is procarboxypeptidase converted into carboxypeptidases
trypsin
how is chymotrypsinogen converted nto chymotrypsin
trypsin
how is pro-elastase converted into elastase
trypsin
how is prophospholipase A converted into phospholipase A
trypsin
