pancreas

Question 1

where are blood vessels located in relation to duct cells

Answer 1

below in interstitium

Question 2

what connects adjacent duct cells

Answer 2

tight junctions

Question 3

mechanism of HCO3- production

Answer 3

CO2 enters cell from blood in interstitial capillaries → reacts with water in cell in presense of carbonic anyhdrase → carbonic acid → dissociates into H+ and HCO3-

Question 4

simultaneous mechanism of watery secretion into duct lumen

Answer 4

Na+ and water move from interstitial capillaries through paracellular pathways and tight junction into lumen → watery secretion in duct lumen

Question 5

mechanism of HCO3- secretion

Answer 5

Cl- within cell moves out via primary active transport through CFTR → Cl-/HCO3- anion exchanger in apical membrane activates as Cl- moves down concentration gradient back into cell, and HCO3- moves out down its concentration gradient (secondary active transport)

Question 6

fate of H+ in duct cells

Answer 6

move out through basolateral membrane into bloodstream via Na+/H+ exchange down concentrations gradient (secondary active transport); no change in membrane potential as both have a single charge

Question 7

fate of Na+ in duct cells

Answer 7

Na+/K+ ATPase pumps K+ in and Na+ out to maintain Na+ and osmotic gradient

Question 8

fate of K+ in duct cells

Answer 8

move out via primary active transport through K+ channels

Question 9

movement of ions in duct cells vs parietal cells

Answer 9

duct cell: H+ into blood, HCO3- into lumen; parietal cells: H+ into lumen, HCO3- into blood

Question 10

effect of movement of ions on stomach and pancreatic venous blood

Answer 10

stomach venous blood is more alkali, pancreatic venous blood is more acidic

Question 11

mixutre of zymogens

Answer 11

protease, trypsinogen, procolipase (coenzyme for lipid digestion)

Question 12

example of protease zymogens

Answer 12

chymotrypsinogen, procarboxypeptidase

Question 13

active enzymes in zymogens

Answer 13

pancreatic amylase, lipase

Question 14

active form of trypsinogen

Answer 14

trypsin

Question 15

what converts trypsinogen to trypsin in duodenum

Answer 15

brush border enzyme enterokinase

Question 16

what does trypsin catalyse conversion of

Answer 16

protease zymogens into proteases, procolipase into colipase, autocatalysis of trypsinogen into trypsin

Question 17

what else is secreted from pancreas in zymogen granules

Answer 17

trypsin inhibitor

Question 18

function of pancreatic amylase

Answer 18

conversion of polysaccharides into disaccharides in duodenum

Question 19

fate of disaccharides

Answer 19

conversion into monosaccharides for absorption

Question 20

function of proteases

Answer 20

conversion of peptides into shorter peptides

Question 21

fate of shorter peptides

Answer 21

brush border dipeptidases convert into amino acids for absorption

Question 22

function of lipase

Answer 22

comvert triglycerides produced by emulsification with bile to fatty acids and monoglycerides for absorption

Question 23

acute pancreatitis as an effect of pancreatic duct obstruction (e.g. gall stone)

Answer 23

accumulation of zymogen enzymes overwhelms trypsin inhibitor, causing trypsin to be produced, leading to pancreatic auto-digestion, leading to acute pancreatitis