Flashcards in lecture 11: liver structure/fxn Deck (27):
what are the central metabolic functions of the liver?
protein metabolism + synthesis
describe carbohydrate metabolism
synthesis + storage of glycogen
conversion of galactose and fructose into glucose
describe fat metabolism
fatty acid oxidation
describe protein metabolism/synthesis
plasma protein synthesis (albumin, clotting factors)
amino acid synthesis
what are other key liver functions?
waste formation + excretion into bile
storage/modification of vitamins + iron
what does the portal triad contain?
+ lymphatic vessels + branches of vagus nerve
where does blood flow from hepatic portal vein and the branch of hepatic artery in the portal triad?
both flow into liver
what are the functional units of the liver?
classic hepatic lobule
how frequently is each functional unit of the liver used?
classic hepatic lobule = most common
portal lobule = rarely used
liver acinus = sometimes used
Describe functional units of liver
classic hepatic lobule: drains blood from portal vein + hepatic artery to hepatic or central vein
portal lobule: drains bile from hepatocytes to the bile duct
liver acinus: supplies oxygenated blood to hepatocytes
compare the centers and fluids of each functional unit of the liver
classic hepatic lobule:
center = outflow; fluid = venous blood
center = outflow; fluid = bile
center = inflow; fluid = portal + arterial blood
what is the liver acinus supplied by?
branches of hepatic artery
which zone of liver acinus are hepatocytes least oxygenated?
zone III (closest to central/hepatic vein)
What are the major cell types in the liver? what is their function?
hepatocytes = multiple metabolic/biosynthetic functions
endothelial cells = barrier b/w blood + hepatocytes, CL of macromolecules
stellate (ito) cells = retinoid storage, release; liver growth, regeneration, cirrhosis
Kuupffer cells: resident macrophages
biliary epithelial cells
describe localization of liver cell types relative to sinusoids
sinusoids are lined by endothelial cells.
kupffer cells flow through sinusoids, while stellate cells sit between endothelial cell and hepatocytes
describe the polarization of hepatocytes
3 functional sides:
1) basal area exposed to perisinusoidal space
2) lateral contact w/ other liver cells
3) apical area exposed to biliary canaliculi
do the endothelial cells have filtration barriers for blood?
no, just for cells
what is the perisinusoidal space?
extracellular space between fenestrated sinusoidal endothelium and the basolateral side of hepatocytes
where are Ito/hepatic stellate cells (HSC) located?
what do activated HSC cells produce?
extracellular matrix which is important for normal liver regeneration (but also cirrhosis development)
where are kupffer cells located?
located within sinusoids and in contact with endothelial cells
what are functions of the biliary tract?
(1) conduit for bile from liver to small intestine
(2) bile modification and storage
describe the functions of biliary tract
(1) efficient lipid digestion and absorption requires bile acids for micelle formation
(2) bile modification: gallbladder inc. [bile] and decreases [Cl, HCO3]; gallbladder will contract with meal ingestion to provide bile for fat digestion/absorption
what are the biliary canaliculi formed by?
apical sides (microvilli) of two adjacent hepatocytes
what are the name of the biliary duct epithelial cells?
what is missing from gallbladder histology?
muscularis mucosa and submucosa
villi, goblet and paneth cells