GI Physiology: Pancreas Flashcards
Name a congenital disease that results in pancreatic insufficiency.
CF
The majority (85%) of the pancreas is involved in ________.
digestion
Which pancreatic enzymes are released in inactive form? Why is this?
All the proteolytic enzymes are - because they are potent (especially trypsin - it activates all the others)
What is responsible for the bulk of protein digestion? Where does this occur?
Pancreatic proteases in the proximal small intestine.
What enzyme is primarily responsible for activation of trypsinogen –> trypsin? Where exactly is this enzyme found?
Enterokinase - it is a membrane-bound enzyme found in the proximal small intestine.
Which pancreatic enzyme can convert all the other pancreatic proteases to their active forms?
Trypsin
What is the point of releasing trypsin inhibitor along with trypsinogen?
To protect against any small amounts of premature trypsinogen –> trypsin activation.
Pancreatic lipase cleaves TAGs into ______ and ______.
2-MAGs and FFAs
Can vertebrates digest cellulose?
Nope
Which phase of digestion is responsible for the majority of the stimulation of pancreatic secretion?
Intestinal!
Which hormones/substances stimulate pancreatic ductal cells and which ones stimulate pancreatic acinar cells?
CCK and Ach (from vagus nerve) stimualtes ACINAR cells to release enzymes.
Secretin stimulates DUCTAL cells to make bicarbonate and fluid.
What stimulates “i” cells in the small intestine to release CCK into the bloodstream?
- AAs/peptides
- Fatty acids
- H+ in the duodenum
1 and 2 mostly
What stimulates “s” cells in the small intestine to release secretin into the bloodstream?
Fatty acids and H+ (duodenal acid load)
Describe how the concentrations of HCO3- and Cl- change as pancreatic secretory rate increases. Explain why.
HCO3- concentration increases and Cl- decreases because the ductal cells use a HCO3-/Cl- exchanger and ductal cell stimulation results in a large increase in bicarb and fluid secretion.
Why does the concentration of amylase decrease upon pancreatic secretion?
Because the increase in fluid secretion upon stimulation of ductal cells outweighs the corresponding increase of enzyme secretion by acinar cells, so amylase is diluted.
