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