Accessory Gland Secretions Flashcards
What are the general classes of enzymes released by the acinar region of the exocrine pancreas?
Proteases, amylolytic enzyme, lipases, nucleases, (trypsin inhibitor)
What is secreted from the ductular region of the pancreas?
Bicarbonate
What stimulates the secretion of bicarbonate from the pancreas?
Acidity induces secretion of secretin which stimulates pancreatic bicarbonate secretion
How is pancreatic enzyme secretion stimulated?
CCK production (stimulated by AA and FA) stimulates enzyme secretion of pancreas
True or False: All of the proteases produced in the pancreas are in zymogen form
True
Where is enterokinase produced and what is its function?
Produced by enterocytes in the intestinal wall near the brush border, and it will cleave trypsinogen to trypsin
What pancreatic enzyme activates all other pancreatic enzymes?
Trypsin
Do pancreatic enzymes prefer an acidic, neutral, or alkaline pH?
Alkaline
Through what pathway do CCK and ACh mediate typical exocrine gland secretion?
DAG-IP3 pathway–> Ca++ release
Through what pathway do VIP and secretin mediate typical exocrine gland secretion?
cAMP pathway
What pancreatic secretory processes are happening during the cephalic and gastric phases of digestion?
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
What pancreatic secretory processes are happening in the intestinal phase of digestion?
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
How is bile entry into the duodenum stimulated?
Fatty acids in the duodenum increases CCK secretion which stimulates gall bladder contraction and sphincter of Oddi relaxation
Bile enhances of intestinal absorption of what?
Lipids, Ca++, and Fe++
What solutes are excreted through bile?
Cholesterol, bilirubin, xenobiotics, plant sterols, immune complexes, IgA
Where is bile formed?
In the canaliculus of the liver
How much bile is produced a day?
500 mL
What is the difference between hepatic bile, canilicular bile, and bile in the gallbladder?
Hepatic bile is canalicular bile plus the ductular modification, and the gallbladder contains concentrated and acidified hepatic bile
What are the primary bile salts?
Cholate and chenodeoxycholate
What are the major molecules conjugated to bile acids to form bile salts?
Glycine and taurine
What is the relative osmolarity of hepatic bile?
Isosmotic
What are the functions of the bile ductules?
Conduits for bile, osmotic equilibrium of bile, secretion of bicarbonate, mucus, and IgA, absorption of amino acids and glucose, hydrolysis of oxidized glutathione
What are the roles of bile acids in biliary secretion?
Induction of vesicular secretion of cholesterol and canalicular contractions, solubilize vesicles and bind other amphathic molecules, bind heavy metals
How is bile concentrated in the gall bladder?
Isosmotic absorption of Na+, Cl- and H20
