PANCREAS ANATOMYstomachesophagusductus choledocusduodenumduct of Santoriniduct of Wirsungpancreas
PANCREATIC SECRETIONS1. PROTEASES (70%)Endopeptidases (trypsin, chymotrypsin, elastases)Exopeptidases (carboxypeptidases)trypsinogen trypsin activates all other precursorsenterokinase(duct walls)2. NUCLEASES (DNAase, RNAase)3. PANCREATIC AMYLASE (hydrolyse starch and gl;ycogen)4. PANCREATIC LIPASE (triglycerides fatty acids and glycerol)
REGULATION OF SECRETION1. SECRETINfood instomachrelease ofstomach acidinto duodenumrelease of secretininto blood byduodenal cellssecretion ofbicarbonateby duct cellsalkaline pH(ideal forpancreatic enzymes)2. PANCREOZYMIN (cholecystokinen)amino acids andfats in intestinerelease of pancreozyminby intestinal mucosa into bloodrelase of pancreatic enzymesinto the intestine3. GASTRINfood in stomachgastrin secretionby stomach mucosarelease of pancreatic enzymesinto the intestine4. AUTONOMIC INNERVATION (vagus nerve)
PANCREAS (PANORAMIC)pancreatic aciniislet ofLangerhansislet ofLangerhansBVpancreatic lobe
PANCREATIC SECRETORY DUCTS LARGE SECRETORY DUCT INTERLOBULAR DUCTacinussimplecuboidalepitheliumsimplecolumnarepithelium
EXOCRINE PANCREASinterlobular ductintercalatedductnerveacinuspyramidalsecretorycellbasal basophilia(rough ER)zymogengranulescentro-acinarcellsblood vesselroughendoplasmicreticulumgolgiapparatusgolgivesiclescondensingvacuoleszymogengranules merocrine secretion(exocytosis)
INTERCALARY DUCTS AND CENTROACINAR CELLSintercalary ductintercalaryductcentroacinarcell
PANCREATIC EXOCRINE SECRETORY CELLzymogengranulescentroacinarcell
CELL BIOLOGY OF PANCREATIC SECRETION1. SYNTHESIS14C -leucine + tRNA14C-amino-acyl tRNAmRNA forchymotrysinogenribosomeschymotrysinogen2. SEGREGATIONmRNAribosomespolypeptideRER cisterna3. INTRACELLULAR TRANSPORTRERtransitionalelementsgolgiapparatusgolgi vesicles4. CONCENTRATIONH2OH2Ocondensing vacuoles5. INTRACELLULARSTORAGEzymogengranules6. DISCHARGEexocytosis
EXPERIMENTAL METHODS IN CELL SECRETION1. SUBCELLULAR FRACTIONATION(grind and find)density gradientcentrifugationzymogengranulescondensingvacuolesgolgimicrosomes(RER)vesiclescpm14Cleucinecpm14Cleucinecpm14CleucineRERgolgicondzymogenRERgolgicondzymogenRERgolgicondzymogen(3 mins)(7 mins)(80 mins)pulse chase2. RADIOAUTOGRAPHY(cook and look)developed silver grainsphotographicemulsionultrathin sectionpancreatic acinar cell
ISLET OF LANGERHANSalpha cellbeta cellbloodcapillaryacinusbeta cellalpha cellfenestratedcapillary(insulin)(glucagon)vascular pole(secretion by exocytosis)INSULIN- increases membrane permeability to glucosepromotes glycogenesisdecrease blood glucose levelsGLUCAGON - promotes glycogenolysisincreases blood glucose levels ANTAGONISTIC HORMONES
ISLET OF LANGERHANS
ISLET OF LANGERHANS - TEM
STAINED ALPHA AND BETA CELLS ALPHA CELLSBETA CELLS