secretory functions of pancreas Flashcards
What inn the islets of langerhans
sympathetic and parasympathetic NS
inhibited by SAN
stimulated by PAN
Where is the sphincter od oddie
at the edge of the hepatopancreatic ampulla
what is a lobule of the pancreas
group of acini
describe the pancreatic drainage into the pancreatic duct
lumen is drained by a ductule which forms interlobular ducts then into pancreatic duct
which cells in the pancreas are responsible for producing large volumes ow watery fluid
the ductule cells and centroacinar cells
What do intercalated ducts receive
secretions from acini
what do intralobular ducts receive
fluid from intercalated ducts
Descirbe the two components of pancreatic secretion
aqeuous NaHCO3 component to neutralize
enzymatic component to digest a meal
What hormones stimulate protein secretion from acinar cells
ACh, CCK secretin and VIP
What do VIP and secretin stimulate
activate PKA
What do CCK and ACH activate
PLC and PKC
What does CCK stimulate on acinar cells
enzyme secretion
Any activation of acinar cells results in what
increase Ca as a second messenger
activation of protein kinases
and increase acinar cell secretions
Is the fluid from acinar cells hypo, hyper or isotonic
isotonic, NaCL secretion
Which cells are responsible for the release of HCO3
duct cells
How does secretin increase secretion of HCO3
activates adenylyl cyclase which increases cAMP to stimulae PKA and phosphorylates the CFTR which pumps out Cl so that the ClHCO3 counter transporter has larger gradient
What enayme is necessary for carb digestion
amylase activated by Cl
What are the 2 main protein enzymes
tyrpsinogen and chymotrypsinogens
What is the enzyme for lipid digestion
lipase
What enzyme removes the bile salts from around the fat droplets so lipase can degrade them
pro-colipase
what do glycoproteins do after secreted by acinar cells
protect against protease mediated mucosal injury
what fo trypsin inhibitors dow
protect against trypsin in acinar and ductal cells
trypsin does what to the enzymes
activates chymotrypsinogen
What activates trypsinogen to trypsin
enterokinase
where is enterokinase located
brushborder of duodenum
What are the primary roles of secretin and CCK
secretin for fluid and electrolyte secretion
CCK for enzyme secretion
what dictates the amount of fluid and HCO3 secretion
quantity of acid enter in duodenum
What determines the amount of enzyme secretion
quantity of fat and protein in the duodenum
describe stimulation of CCK
CCK b R via sitmulation from vagal afferents of duodenum that then release ACh and VIP to stimulate HCO3 secretion from duct cells
What is CCK effect on sphincter of oddi
relaxes it
what is CCK effect on stomach? gall bladder?
on stomach is reduced emptying
on gall bladder is contraction
Where is CCK stored
I cells in duodenum
What controls release of CCK
its releasing peptide and monitoring peptide
Ach and vasovagal reflexes release gastrin-releasing peptide which inturn stim CCK RP and MP
What inhibits I cells from releaseing CCK
trypsin
Where is secretin released from
S cells in duodenal mucosa
What is secreted at highger and lower rates under secretin stimulation
increased Na HCO3 secretion
decreased K Cl secretion
At high rates of secretion describe general composition of pancreatic juice
alkaline
What stimulates S cells to secrete secretin
when pH falls from gastric acid
fatty acid meals
What occurs to secretin when on a proton pump inhibitor
bicarb is not released nor secretin so too much acid– ulcer
What is Achlorhydric
unable to secrete gastric acid
What is the main hormone to counter the acidity coming from stomach
secretin
In what phase is majority of pancreatic secretion occuring in
the intestinal
When you eat a high fat and protein meal what hormone primarily takes over
CCK to acinar cells to release pancreatic enzymes
Signs of malabsorption and ingestion appear when pancreatic secretions fall below what percent
10
What is Steatorrhea
fat in the stool, early sign of pancreatic digestion
what can cause steatorrhea
reduced pancreatic enzyme, lipase and bicarb secretion
a low pH inactivates lipase
What is pancreatitis
autodigestion of pancreatic tissue when retaining the secretions
acute could be caused by a gall stone
hereditary could be mutated trypsin
or alcohol abuse causing chronic inflammation
What drugs and toxins can damage pancreas
immunosuppressants, anticonvulsants, thiazides
What are autoimmune diseases of the pancreas
celiacs, IgG4
What type of genetic mutations occur to lead to pacreatitis
SPINK1, CFTR and CTRC
Describe cystic fibrosis mutation of pancreas
the CFTR is lacking so Cl does not leave and then decreased HCO3 excretion–> autodigestion
How does primary aldosteronism affect pancreas
abnormal electrolyte levels
low NaCl in saliva and K is at high levels
What is Kwashiokor
reduction in pancreatic secretion except amylase (cannot digest protein)
What happens to pancreas in diabetes
reduced pancreatic enzyme secretion in absence of pancreatic disease
What cells are the main key players in pancreatic secretion during the cephalic phase
the acinar cells, high concentration of enzymes in low volume
What is the only enzyme in digestive system that can digest fat
pancreatic lipase
