Pancreatic Function and Secreton Flashcards
Purpose of pancreas
Lubricaiton and protection of mucosa
Enzymatic hydrolases and catalyzes just about everything
Neutrilization of acidic contents in intestine coming from the stomach…maintain proper pH
Exocrine and endocrine of the pancreaes
Exocrine set up with ductal cells (produce bicarbonate) and exocrine cells (produce enzymes)
Endocrine functions important in metablism
Endocrine function cells
Insulin - beta cells Glucagon - alpha cells Somatostatin - delta cells Panc polypeptide VIP Sometimes G cells...potential gastrinoma...in Zollinger-ellison, no feedback inhibition of acid secretion like there is for G cells of gastric mucosa
Enzymatic secretions
FOrmed in acinar cells…major stimulus is CCK with a little vagus drive
CCK released by intestinal mucosal epithelial cells in response to fats….release increased by CCK-RP by enterocytes and by monitor peptide forom pancreas
All released by exocytosis
Some enzymes taken up by intestinal mucosa and reciruclated and some are digested
Acinar and duct structure similar to salivary glands
Types of enzymatic secretions
Proteases…trypsinogen converted by enteropeptidase by trypsin…trypsin inhibitor to prevent autodigestion
Chymotrypsinogen
Procarboxypeptidase A and B
Panc amylase - starch to disacc
Lipases
Colipase - displace bile salt so lipases can act
Nucleases and proelastase
Electrolyte secretions
From ductal cells
High in HCO3 and needs carbonic anhydrase and CO2 from circulation
Results in acid tide leaving the pancreas….goes ot liver to mix with stomach alkaline tide…normally no NET change in H and HCO3 in blood or GI tract
Electrolyte secretory control
Separate control from enzymatic secretions
Primary is secretin…stimulated by presence of aicd in intestine
Weak stimulus by CCK and Ach
Phases of regulation
Interdig - ongoign enzyme synthesis but little release
Ceph - vagal mediated release of enzymes (Ach)
Gastric - weak stimulation by gastrin and Ach
Intestinal - Secretin - major effect to dec acid and inc bicarb so stimulation of duct cells
CCK - inc enzyme syntehsis and release via acinar cells
Secretin source stim, receptors, 2nd mess, trophic effect, effects
S cells of intestinal
Acid, AA
Membrane bound
cAMP
None
Electrolyte secretions wthrough ductal
CCK stim, source, recept, 2nd mess, trophic, effects
I cells of intestinal mucosa
AA, FA, Ach, dec by trypsin
Membrane bound
IP3/Ca - cGMP
Inc pancreatic growth
Enzymatic secretions and acinar cells
CCK secretion
BY the I cells…stimualted by release of CCK-RP from other duodenal mucosa cells
Monitor peptide release by pancreatic acinar cells when stimulated to…increase their enzyme synthesis…cephalic phase neural stim inc enzymes syntehsis and release MP into lumen and into duodenum where it stimulates CCK
CCK effects
Gallbladder contraction
Pancreas acinar secretion
Stomach reduced emptying
Sphincter of oddi relaxation
ALL of this is working to digest and match delivery to digestive and absorptiive cpaacity
Dysfunctions
Pancreatitis
Diabetes
Peptic ulcers - gastric vs Duodenal**
Loss of lipase - steatorrhea
