Accessory Gland Secretions

Question 1

What are the general classes of enzymes released by the acinar region of the exocrine pancreas?

Answer 1

Proteases, amylolytic enzyme, lipases, nucleases, (trypsin inhibitor)

Question 2

What is secreted from the ductular region of the pancreas?

Answer 2

Bicarbonate

Question 3

What stimulates the secretion of bicarbonate from the pancreas?

Answer 3

Acidity induces secretion of secretin which stimulates pancreatic bicarbonate secretion

Question 4

How is pancreatic enzyme secretion stimulated?

Answer 4

CCK production (stimulated by AA and FA) stimulates enzyme secretion of pancreas

Question 5

True or False: All of the proteases produced in the pancreas are in zymogen form

Answer 5

True

Question 6

Where is enterokinase produced and what is its function?

Answer 6

Produced by enterocytes in the intestinal wall near the brush border, and it will cleave trypsinogen to trypsin

Question 7

What pancreatic enzyme activates all other pancreatic enzymes?

Answer 7

Trypsin

Question 8

Do pancreatic enzymes prefer an acidic, neutral, or alkaline pH?

Answer 8

Alkaline

Question 9

Through what pathway do CCK and ACh mediate typical exocrine gland secretion?

Answer 9

DAG-IP3 pathway–> Ca++ release

Question 10

Through what pathway do VIP and secretin mediate typical exocrine gland secretion?

Answer 10

cAMP pathway

Question 11

What pancreatic secretory processes are happening during the cephalic and gastric phases of digestion?

Answer 11

gastrin release that binds to CCKa and ACh release that binds to M3 in pancreatic acinar cells stimulating water and enzymes being released into the lumen of the acinus;

ACh binding to M3 in pancreatic duct cells secretes bicarb into the mixture

Question 12

What pancreatic secretory processes are happening in the intestinal phase of digestion?

Answer 12

Protein and lipid breakdown products

1) stimulate a vagovagal reflex that stimulates acinar cells through ACh,

2) stimulate I cells in the duodenum to secrete CCK, stimulating acinar cells;
H+ stimulates duodenal S cells to produce secretin, stimulating bicarb production;

Also fat and protein bind CCKa to make CCK

Question 13

How is bile entry into the duodenum stimulated?

Answer 13

Fatty acids in the duodenum increases CCK secretion which stimulates gall bladder contraction and sphincter of Oddi relaxation

Question 14

Bile enhances of intestinal absorption of what?

Answer 14

Lipids, Ca++, and Fe++

Question 15

What solutes are excreted through bile?

Answer 15

Cholesterol, bilirubin, xenobiotics, plant sterols, immune complexes, IgA

Question 16

Where is bile formed?

Answer 16

In the canaliculus of the liver

Question 17

How much bile is produced a day?

Answer 17

500 mL

Question 18

What is the difference between hepatic bile, canilicular bile, and bile in the gallbladder?

Answer 18

Hepatic bile is canalicular bile plus the ductular modification, and the gallbladder contains concentrated and acidified hepatic bile

Question 19

What are the primary bile salts?

Answer 19

Cholate and chenodeoxycholate

Question 20

What are the major molecules conjugated to bile acids to form bile salts?

Answer 20

Glycine and taurine

Question 21

What is the relative osmolarity of hepatic bile?

Answer 21

Isosmotic

Question 22

What are the functions of the bile ductules?

Answer 22

Conduits for bile, osmotic equilibrium of bile, secretion of bicarbonate, mucus, and IgA, absorption of amino acids and glucose, hydrolysis of oxidized glutathione

Question 23

What are the roles of bile acids in biliary secretion?

Answer 23

Induction of vesicular secretion of cholesterol and canalicular contractions, solubilize vesicles and bind other amphathic molecules, bind heavy metals

Question 24

How is bile concentrated in the gall bladder?

Answer 24

Isosmotic absorption of Na+, Cl- and H20

Question 25

What is the mechanism by which bicarbonate is secreted by pancreatic ductal cells?

Answer 25

Secretin binds to its receptor which stimulates cAMP production leading to activation of the CFTR channel, exporting Cl- from the cell which is then exchanged for bicarb produced by carbonic anhydrase through the Cl-/bicarb transporter

Question 26

What is secreted into the bile by the gall bladder?

Answer 26

Mucins and H+

Question 27

Why is the protenation of bile important? What are the most important substrates protenated?

Answer 27

Decreases concentrations of anions that are prone to precipitate with Ca++ for form gallstones;

Carbonate and unconjugated bilirubin

Question 28

How does the osmolarity of bile change as it is concentrated in the gall bladder?

Answer 28

It remains the same

Question 29

What happens to micelles of amphipathic molecules as they get more and more concentrated?

Answer 29

They increase in size

Question 30

What is the critical micellar concentration?

Answer 30

The concentration at which micelles start to clump together to form larger and larger miscelles

Question 31

Where and how are bile acids reabsorbed? What maintains the force of this movement?

Answer 31

Absorbed through the BA-/Na+ apical cotransporter on terminal ileal enterocytes and then go back into circulation via the BA-/Anion exchanger on the BL membrane; Na+/K+ ATPase

Question 32

What are the two methods by which cholesterol can be excreted?

Answer 32

60% of excreted is excreted in feces as neutral sterols;

other 40% through feces as acidic sterols