Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
36 Cards in this Set
- Front
- Back
Is fluid hyperosmotic or hyposmotic when it leaves the stomach?
|
hyperosmotic
|
|
What area is considered to be the endocrine portion of the pancreas and what do they secrete?
|
islets of langerhans - secrete insulin, somatostatin, glucagon, and pancreatic polypeptide; these are all secreted into blood
|
|
What is secreted from the exocrine pancreas?
|
enzyme, water, HCO3- secretion into pancreatic and common bile duct and thru sphincter of oddi
|
|
What is the purpose of having both acinar and duct cells providing secretion in the pancreas?
|
acinar cells - secrete enzymes
ductile cells - secrete water and electrolytes ** having 2 different secretion systems allows better adjustment of enzyme/liquid components |
|
What is the significance of osmolarity dropping rapidly in the duodenum?
|
1) maintains fluid balance
2) provide digestive enzymes with ideal conditions 3) protection of mucosa |
|
What is the difference between proximal and distal duct cells in the pancreas?
|
proximal duct cells - secrete water and bicarbinate
distal duct cells - reabsorbs water and bicarbonate |
|
What is the effect of increased flow rate on pancreatic secretions?
|
1) high rates - net secretion is high in bicarbonate and low in chloride - reflective of primary secretion
2) vice versa at low rates - secondary secretion *virually no change in cations wih change in flow rate |
|
What is stored in a zymogen granule?
|
inactive proteolytic enzymes (proenzyme), and a trypsin inhibior (to avoid autodigestion of the pancreas)
|
|
What are the different types of enzymes found in the exocrine pancreas?
|
1) lipolytic (dig lipids)
2) amylases (dig CHO) 3) proteolytic (dig proteins) |
|
What does pancreatic lipase do?
|
1) splits TGs into glycerol and FFAs (2FAs and a 2-monoglyceride)
2) requires oil/water interface, bile salts, and colipase |
|
What linkage does pancreatic amylase cleave?
|
alpha 1,4 linkage of starch (creates maltose, maltotriose etc.)
|
|
Trypsin, chymotrypsin, and carboxypeptidase A and B are considered to be what general type of pancreatic enzyme?
|
proteolytic (digests proteins)
|
|
Describe the action of trypsin.
|
Endopeptidase active at basic amino acids.
|
|
Describe the action of chymotrypsin.
|
Endopeptidase active at aromatic amino acids.
|
|
Describe the action of carboxypeptidase A & B.
|
Exopeptidases active at C-term end; A active at aromatic and neutral amino acids and B active at basic amino acids
|
|
When pancreatic cells release granules, do all have the same % of enzymes?
|
YES!
|
|
What type of pancreatic enzymes make up 75% of the pancreatic enzymes?
|
Proteolytic (proteases including endopeptidases, and exopeptidases)
|
|
Which is a more important method of pancreatic secretion control, neural or hormonal?
|
Hormonal (secretin, CCK, and PP)
|
|
What pH triggers the release of secretin from the mucosal cells?
|
pH<4 in the duodenal lumen
|
|
Which hormones/neural peptides bind to Acinar cells? via their receptors that are located there?
|
1) VIP
2) GRP 3) CCK 4) ACh |
|
Which hormones/neural peptides bind to duct cell in the pancreas via their receptors that are located there?
|
1) secretin
2) ACh |
|
What cells does secretin stimulate to secrete bicarbonate and water?
|
1) pancreatic duct cells
2) duodenal glands 3) hepatocytes |
|
What receptors does CCK act on in the pancreas?
|
CCK-A receptors
|
|
What type of response does most of CCKs activity come from?
|
long arc vago-vagal reflex
|
|
When is PP secreted and what does it do?
|
pancreatic polypeptide (PP) is an inhibitory regulator (inhibits vagal output from CNS)that is secreted during the meal and turns off the excitatory inputs on acinar cells
*proximal feedback loop |
|
What is PYY and when is it secreted?
|
PYY is secreted from the ileum after a meal and inhibis gastric acid secretion, pancreatic enzyme secretion, and decreases transport
*distal feedback loop |
|
What are the 3 phases of postprandial pancreatic secretion?
|
1) cephalic (25% of response)
2) gastric (10%) 3) intestinal (50-75%) |
|
Which pancreatic secretion phases are neurally regulated and which are hormonally regulated?
|
1) neural - cephalic and gastric
2) hormonal - intestinal |
|
Explain stimulus secretion coupling of pancreatic acinar cell secretion.
|
Receptors for two different things (ex. VIP and secretin) couple throuh the same pathway (ex. G protien) and potentiate each other.
|
|
How much fluid is secreted by enterocytes/day?
|
1000ml/day
(about 3000 ml total is secreted into the intestine, but much of that is from non-enterycte origin) |
|
Where is the oldest enterocyte located on a villus structure?
|
at the tip of the villus where it will be sloughed off
|
|
Explain how the enterocyte changes its function as it moves up the villus.
|
crypt - net secretory cell
tip - net absorptive cell |
|
What ion is coupled with the secretion of water in an enterocyte?
|
Cl-
(via the cystic fibrosis transmembrane regulator (CFTR) on the apical membrane) |
|
How does cholera toxin work?
|
irreversibly activates G protein coupled to adenylate cyclase, increasing cAMP and keeping CFTR channel open (lose Cl-, Na+, and water)
|
|
What makes up most of the colonic secretion?
|
mucus
|
|
What does interdigestive secretion do?
|
gastric, bilary, and pancreatic fluid and enzymes is released periodically between meals to clear and clean the gut
|