Histology of pancreas, liver, gall bladder Flashcards
two “parts” of pancreas? what are the fundamental units of each? which predominates?
endocrine- islets of langerhans (mostly in tail). exocrine-acini. Exocrine is vast majority
how are pancreatic proteases activated?
enterokinase in brush border converts trypsinogen to trypsin which then activates the other zymogens
centroacinar cells
line duct and extend into central lumen of acinus. Secrete HCO3-
Three major classes of endocrine cells and their function
Alpha: glucagon (raises blood glucose). Beta: zinc-insulin granules (lowers it). Delta: somatostatin (inhibits insulin and glucagon)
autonomic effect on endocrine pancreas
sympathetic: stimulates glucagon, inhibits insulin. Parasympathetic: stimulates both
organization of classic liver lobule
hexagon with central vein and vessels (hepatic artery, portal vein, bile duct) at each corner. In between are single-layered hepatocytes forming sinusoids through which blood percolates
space of disse
between sinusoidal cell microvilli and the fenestrated endothelium. Basically lymphatic
three surfaces of hepatocyte
2 sinusoidal (basal) surfaces, 4 lateral surfaces, bile canalicular (apical) surface which wrap in “belts around cell” and are sealed by tight jxns
bile constituents
bile salts (cholesterol derivatives) to emulsify. Pigment from glucuronidated bilirubin from heme breakdown. Plasma proteins and IgA
kupffer cells
resident tissue macrophages. Line the sinusoids. Digest old RBCs
lipocytes (ito cells)
in space of disse. store vit A in their lipid droplets
what does liver do with fatty acids
makes them into VLDL in golgi then secretes them into blood
how does gall bladder concentrate bile
Na and Cl enter cells and are pumped out basolateral membrane. Water follow.
unique histology of gall bladder
no muscularis mucosae or submucosa
how is bile released
CCK secreted after meal causes sphincter of Oddi relaxation, gall bladder contraction
