Secretory functions of the pancreas (choudhury)

Question 1

what are the cells of the endocrine portion of the pancreas

Answer 1

islet cells of langerhan

Question 2

what are the cells of the exocrine portion of the pancreas

Answer 2

acinar cells

duct cells

Question 3

what do acinar cells secrete in the pancreas

Answer 3

pancreatic enzymes

Question 4

what do duct cells in the pancreas secrete

Answer 4

aqueous NaHCO3- solution

Question 5

what cells of the pancreas produce glucagon

Answer 5

alpha (A cells)

Question 6

what cells of the pancreas produce insulin

Answer 6

Beta (B cells)

Question 7

what cells of the pancreas produce somatostatin

Answer 7

D cells

Question 8

what cells of the pancreas produce pancreatic polypeptide

Answer 8

pp cells

Question 9

what is the effect of sympathetics on pancreas?

parasympathetics ?

Answer 9

inhibited by sympathetic &
-
stimulated by parasympathetic NS

Question 10

what are the two ducts of the pancreas?

Answer 10

main pancreatic duct (Wirsung’s)

accessory collecting duct (Duct of Santorini)

Question 11

what are the two components of exocrine secretions ?

Answer 11

aqueous bicarb component

enzymatic component

Question 12

what stimulates the release of the aqueous component of the pancreatic juice

Answer 12

secretin

Question 13

which factors stimulate acinar cells to secrete protein (enzymatic protein)

how do they increase the secretion?

Answer 13

ACh
CCK
Secretin
VIP

All increase intracellular Ca 2+ (second messenger) which helps vesicles fuse and release contents

Activation of protein kinases increases acinar cell secretion

all of this is to help digest fats, carbs and proteins that are in the duodenum

Question 14

what is the composition of acinar cell fluid

Answer 14

isotonic

Question 15

what are the effects of ACh and CCK on the acinar cells

Answer 15

stimulate NaCl secretion through phosphorylation of ion channels

Question 16

what is the mechanism of action of secretin on ductal cells.

Answer 16

generates electrical gradient that favors Na HCO3- co-transport

(activates adenylyl cyclase, raises CAMP, stimulates protein kinase A and phosphorylates CFTR

Question 17

what are 6 enzymes in the acinar enzymatic secretions

Answer 17

amylase- carbohydrates
trypsinogen- proteins
lipase- triglycerides **very important only one lipase

procolipase (colipase)- removes the bile from the fat particles to make room for lipase to come in and break down the fat

trypsin inhibitors = protects against trypsin in acinar and ductal cells

glycoproteins = protects against protease (mediated mucosal immunity)

Question 18

how are pancreatic proteases activated

where is enterokinase located

Answer 18

enterokinase cleaves a hexapeptide from trypsinogen converting it to active enzyme trypsin

pancreatic proteases are secreted into the duodenum as inactive precursor

enterokinase is located in brush border of duodenal enterocytes (intestinal mucosal cells)

Question 19

what are the effects of CCK

Answer 19

coordinates GI activity (secretion) to food
 contracts gall bladder
 relaxes the sphincter of Oddi
 slows gastric motility 
 retards gastric emptying

the outcome of this is that there is matching of nutrient delivery to digestive and absorptive capacity

Question 20

what molecules stimulate CCK release

Answer 20

CCK-RP and MP which are both proteins

Question 21

what do GRP and ACh stimulate the release of

Answer 21

MP

Question 22

what is the signficance of peptide (protein) factors regulating CCK release

Answer 22

this is important so that CCK can inhibit its own release and doesn’t cause digestion of the lumen

Question 23

what cells release CCK

Answer 23

I cells

Question 24

what cells release secretin

Answer 24

s cells in duodenal mucosa

Question 25

at high rates of secretion what is the composition of pancreatic juice

Answer 25

alkaline

Question 26

what is achlorhydric. what is it caused by what can it lead to

Answer 26

Achlorhydric (unable to secrete gastric acid)
causes:
- secondary to disease
- on drugs, proton pump inhibitors,bicarbonate
fail to release secretin even in presence of a
fatty meal

leads to Duodenal ulcer b/c secretin levels are too low (not enough bicarb release)

Question 27

at what point do signs of malabsorption and indigestion appear

Answer 27

if pancreatic secretions fall below 10 percent

Question 28

what are two important causes of pancreatitis

Answer 28

alcohol (too many triglycerides and ca)

gallstones

Question 29

what is cystic fibrosis

what does this lead to

Answer 29

autosomal recessive genetic mutation in the CFTR Cl channel

Primarily affects caucasians
Lack chloride transporter at apical membrane
Leads to decreased water, HCO3, & Cl excretion, with concentration of protein in acinar ducts and blockage…. gland autodigestion/destruction
Progressive pulmonary and pancreatic insufficiency - chronic

Question 30

at low rates of pancreatic secretion what is the composition

Answer 30

na and cl dominate

Question 31

at high rates of pancreatic secretion what two molecules are predominate

Answer 31

Na and HCO3