Pancreas Physiology

Question 1

embryology of the pancreas

Answer 1

arises from two outpouchings of the duodenum
1. dorsal pancreatic primordium
2. ventral pancreatic primordium

Question 2

dorsal pancreatic primordium

Answer 2

distal; develops independently

Question 3

ventral pancreatic primordium

Answer 3

proximal; develops with the liver

Question 4

normal appearance of the pancreas

Answer 4

V-shaped
lobulated
homogenous in color and texture

Question 5

location of the pancreas

Answer 5

gastro-duodenal angle (between duodenum and greater curvature of the stomach)

Question 6

lobes of the pancreas

Answer 6

1. right (attached to descending duodenum)
2. body (point of the V)
3. left (along greater curvature)

Question 7

pancreatic duct

Answer 7

main duct from pancreas to duodenum

opens into the SI at the major duodenal papilla

Question 8

accessory pancreatic duct

Answer 8

opens into SI at the minor duodenal papilla

only in dogs, not in cats/ruminants

Question 9

major duodenal papilla

Answer 9

opening into the duodenum for the common bile duct and pancreatic duct

Question 10

nerve supply to the pancreas

Answer 10

parasympathetic and sympathetic

Question 11

parasympathetic innervation of the pancreas

Answer 11

vagal (vagus nerve + celiac plexus)

stimulates exocrine secretions

Question 12

sympathetic innervation of the pancreas

Answer 12

splanchnic + celiac plexus

stimulates vasoconstriction and pain fibers

Question 13

what structures make up the exocrine pancreas

Answer 13

acinar cells + duct tissue

Question 14

acinar cells

Answer 14

synthesize, store, and secrete digestive enzymes

Question 15

acinar cell structure

Answer 15

apical: zymogen granules
basal: nucleus, rough ER

Question 16

draining ductules

Answer 16

exits for the acinar glands to release products

Question 17

endocrine pancreas structure

Answer 17

islets of langerhans

Question 18

functions of the exocrine pancreas

Answer 18

synthesis and secretion of digestive enzymes

• secrete HCO3-: neutralize gastric contents & provide optimum pH for enzyme activity
• regulate other regions of GI tract
• inhibit bacterial proliferation
• trophic effect on mucosa
• normal degradation of exposed mucosal brush border enzymes
• intrinsic factor
• accumulates zinc from intestines and secretes excess

Question 19

what do acinus acinar cells secrete

Answer 19

Na+, Cl-, water, digestive enzymes

Question 20

are most secreted enzymes active or inactive

Answer 20

inactive

active ones: amylase, lipase

Question 21

trypsin cascade

Answer 21

1. trypsinogen (inactive) gets released from pancreas acinar cells and travels to the small intestine
2. enterokinases in SI brush border activate trypsinogen –> trypsin
3. active trypsin can self-activate and activate other inactive zymogens

Question 22

what do acinus centroacinar (ductal) cells secrete

Answer 22

bicarbonate, water

Question 23

what do the ducts of pancreas glands secrete

Answer 23

bicarbonate, water

Question 24

what are the two main regulators of the exocrine pancreas

Answer 24

1. secretin
2. cholecystokinin

Question 25

secretin

Answer 25

produced by the SI in response to high levels of gastric acid and fatty acids

stimulates pancreas to release water and bicarbonate

Question 26

cholecystokinin

Answer 26

produced by the SI in response to high levels of undigested lipids and amino acid peptides

stimulates pancreas to release digestive enzymes/proenzymes from acinar cells

Question 27

what are 3 mechanisms the pancreas uses to prevent autodigestion

Answer 27

1. sequestration
2. inactive zymogen
3. trypsin inhibitor

Question 28

sequestration

Answer 28

enzymes are separated from the cytoplasm of the acinar cells by membranes

Question 29

inactive zymogen

Answer 29

enzymes that can digest membranes are synthesized and secreted at inactive zymogens that get activated in the small intestine

Question 30

trypsin inhibitor

Answer 30

if cell detect excess trypsin –> acinar cells will produce trypsin inhibitor