Feb19 M1-Histo Liver and Pancreas Flashcards
how liver separated in lobules
CT penetrates and splits it
liver fcts
- endocrine (albumin, transferrin, etc,)
- exocrine (bile, etc.)
- conjugation and elimination
- conversion (T4 to T3)
- hemopoiesis (fetal)
- storage (glycogen, lipids)
liver lobule where bile going
in the triad (on outside of lobule), bile going in opposite direction. duct called cholangiole and then bile duct
lobule histology
- cords of hepatocytes. small canaliculi between adjacent hepatocytes lead to cholangiole
- portal venule and hepatic arteriole lead to capillaries (sinusoids) in the lobule that will join
bile duct cells characteristics (in portal space of the lobule)
cuboidal cells. prominent lumen
charact of sinusoids in lobules
- covered by layer of endothelial cells
- some macrophages there: Kuppfer cells (endocytose RBC,s form particles, etc.)
name of space between hepatocytes and the endothelial cells of the sinusoids
space of Disse
where bile canaliculi are and why don’t reach space of Disse
- between hepatocytes and between hepatocytes plates.
- tight junctions and desmosomes between hepatocytes so can’T go to space of Disse.
hepatocytes EM charact
- MICROVILLI
- peroxisomes (membrane with crystals inside)
- endocytosis with lysosomes, golgi, RER, SER
characteristics of sinusoids (why called like that)
don’t rest on BM. rest on reticular fibers
4 components of endocytic system of the liver
- endocytic vesicle
- endosome
- maturating lysosome
- lysosome
how endocytosis works in the liver
receptor mediated (liver has receptors for almost all hormones in the body to remove them from circulation)
where enzymes (or hormones) digested after endocytosis and what happens to the receptor
- in maturating lysosome
- R sent back to surface (recycled)
important receptors on the liver
R for LDL, HDL, chylomicrons (produced by enterocytes)
what happens when hepatocyte internalizes a chylomicron
- lipids stored in SER
- R sent back to surface to internalize more chylomicrons
organelles of secretory system of hepatocytes
RER: synthesis of proteins like apoB
SER: TGs (and also phospholipids, cholesterol, long chain FAs) sent to golgi apparatus.
bile synthesis and conjugation + bilirubin conjugation
Golgi: apoB conjugated to lipids forming a lipoprotein called VLDL + packs TGs in vesicles
exocytic vesicles
VLDL goes where and what does it contain
goes in sinusoid, contains cholesterol
what happens to VLDL in the blood
- lipoprotein lipase on caps converts it to IDL
- hepatic lipase converts IDL into LDL
what happens to LDL in the blood
- some goes to peripheral tissues (LDL contains cholesterol), they need cholesterol for growth, is an important part of plasma membranes
- rest of LDL goes to liver (LDL-R)
charact of LDL-R on hepatocytes
- almost everyone has mutations, some are more severe
- inefficient LDL-R = cholesterol stays in circulation for longer time. oxidized. macrophages eat it, goes in intima, atherosclerosis, endothelium disruption, clot formation
peroxisome function in hepatocytes
- H2O2 made into H2O and O2
- beta-oxidation of long chain FAs
- catabolism of ETOH
- cholesterol synthesis
- purines break down (AMP, GMP)
SER functions
- send lipids to Golgi
- bile acids synthesis: 1. bile cholesterol + taurine = taurocholic acid
2. bile cholesterol + glycine = glycocholic acid - bilirubin conjugation into glucuronic acid
where SER sends its contents (ultimately)
- lipids to Golgi
- bile salts and conjugated bilirubin to cholangioles (bile canaliculus)
why viral hepatitis causes jaundice
disrupts tight junctions. bilirubin (direct) goes from bile canaliculi to sinusoids
