Pancreatic Exocrine Secretions and Its Control

Question 1

true / false - the pancreas has digestive and metabolic functions

Answer 1

true - the pancreas has exocrine and endocrine functions

Question 2

what do the acinar cells secrete in the pancreas

Answer 2

digestive enzymes

Question 3

how does the pancreas empty into the duodenum

Answer 3

acini form sacs / lobules which are connected to the ductal tree which empties into the duodenum

Question 4

what cells are the intercalcated ducts made from

Answer 4

squamous / cuboidal cells

Question 5

what cells are the intralobular ducts made of

Answer 5

cuboidal / low columnar epithelial cells

Question 6

what cells are the extralobular ducts made from

Answer 6

columnar cells

Question 7

what cells are the interlobular ducts

Answer 7

columnar epithelial / goblet cells

Question 8

what are the exocrine functions of the pancreas

Answer 8

acinar cells secret digestive enzymes (breakdown carbs, fats, proteins and nucleic acids)
enzymes are secreted as zymogens (inactive form) and are activated in the duodenum

Question 9

what are the anion and cation secretions of the pancreas

Answer 9

anion - bicarbonate, Cl-, SO4-, HPO4-

cation- Na+, K+, Ca2+, Mg2+

Question 10

why is pancreatic juice rich in bicarbonate

Answer 10

helps to neutralise gastric acid secretions

Question 11

how is the composition of pancreatic juice modified as it travels through the duct

Answer 11

epithelial cells actively exchange Cl and bicarbonate
H+ is actively eliminated by Na/H exchanger
H+ exchanged for K+ - driven by Na / K+ATPase
H+ neutralises bicarbonate
CO2 and bicarbonate produced in the blood
CO2 diffuses in and forms H2CO3 and H2O
concentration of bicarbonate in pancreatic juice is indirectly proportional to the concentration of bicarbonate produced in the blood

Question 12

what are the enzyme secretions of the pancreas

Answer 12

proteolytic enzymes (trypsin, chymotrypsin and carboxypeptidase)
amylase
lipase
ribonuclease
deoxyribonuclease

Question 13

how are pancreatic secretions controlled

Answer 13

neuroendocrine signals
vagal (parasympathetic) stimulation - enhances the rate of secretion of enzymes and aqueous components of pancreatic juice
sympathetic stimulation - inhibits secretion (decreased blood flow)
secretin and CCK stimulate secretion of pancreatic fluid

Question 14

what is the pancreatic exocrine secretion controlled by in the cephalic phase

Answer 14

vagal (Ach and VIP) stimulation of gastric release from antrum

Question 15

what is the pancreatic exocrine secretion controlled by in the gastric phase

Answer 15

distension (vaso-vagal reflex on fundus or antrum), amino acid and peptide stimulated gastrin secretion

Question 16

what is the pancreatic exocrine secretion controlled by in the intestinal phase

Answer 16

secretion and CCK - enteropancreatic reflexes - acidic chyme in duodenum and jejenum induces secretion of pancreatic juice

Question 17

what does secretin do?

Answer 17

induces pancreatic duct cells to secrete bicarbonate rich pancreatic juice - decreases enzyme content

stimulates bile production

Question 18

what is the role of CCK

Answer 18

stimulates pancreatic acinar cells to synthesise and release enzyme rich pancreatic juice

stimulates the secretion of concentrated bile for fat absorption

CCK contracts the gallbladder and relaxes the sphincter of Oddi - release of bile and some bicarbonate into duodenum
CCK potentiates the effects of secretin which is a weak agonist of acinar cells