hepatobiliary system Flashcards
what does each portal triad contain
branch of hepatic artery
branch of portal vein
bile duct
what does the branch of hepatic artery do
brings O2 rich blood into the liver to support hepatocytes increased energy demands
what does the branch of portal vein do
mixed venous blood from GIT (nutrients, bacteria and toxins) and spleen (waste products)
what does the bile duct do
bile produced by hepatocytes drains into bile canaliculi
coalesce with cholangiocyte lined bile ducts around lobule perimeter
what is the blood supply of the liver (inflow)
dual blood supply
25% hepatic artery
75% portal vein
what is the blood supply of the liver (outflow)
bile
3 x hepatic veins (right, middle and left)
what sits in the inferior tissue of the liver
ligament teres
what is the 3 zone model
blood goes into the hepatic acinus via portal triad (point A)
blood drains out of hepatic acinus via central vein (point B)
hepatocytes near outer hepatic lobule (zone 1) receive early exposure to blood contents :
good components (O2)
bad components - toxins
acinus is split into 3 regions
zone 1 - high O2 and high toxin risk
zone 2 - medium O2 and medium toxin risk
zone 3 - low O2 and low toxin risk
exposure to toxins > hepatocytes in zone 1 die
if the liver becomes ischaemic > hepatocytes in zone 3 die
what are the liver cell types (5)
sinusoidal endothelial cells kupffer cells hepatic stellate cells hepatocytes cholangiocytes
what are sinusoidal endothelial cells
no basement membrane
fenestrated (discontinuous endothelium)
allows lipids and large molecule movement to and from hepatocytes
what are kupffer cells
sinusoidal macrophage cells
attached to endothelial cells ^
plays role in phagocytosis
eliminate and detoxify substances arriving in the liver from portal circulation
what are hepatic stellate cells
ito, perisinusoidal
exist in dormant state
stores vit A in liver cytosolic droplets
activated (fibroblasts) in response to liver damage
proliferate, chemotactic and deposit collagen in ECM
what are hepatocytes
80% of liver mass
cubical
synthesis eg. albumin, clotting factors and bile salts
drug metabolism
receive nutrients and building blocks from sinusoids to synthesise and metabolise
metabolic functions
what are cholangiocytes
secretes bicarbonate (HCO3-) and H2O into bile line the biliary ducts
what are the 3 hepatocyte functions
1) metabolic and catabolic functions
synthesis and utilisation of carbohydrates, lipids and proteins
2) secretory and excretory functions
synthesis and secretions of proteins, bile and waste products
3) detoxification and immunological functions
breakdown of ingested pathogens and processing drugs
what is glycolysis
anaerobic conversion of glucose to lactate (RBCs, renal medulla and skeletal muscle)
aerobic oxidation of glucose (CNS, heart, skeletal muscle and most organs)
what is glycogenesis
synthesis of glycogen from glucose (liver and muscle)
what is glycogenolysis
breakdown of glycogen to glucose
what is gluconeogenesis
production of glucose from non sugar molecules
amino acids (glutamine) in liver and renal cortex
lactate (from anaerobic glycolysis in RBCs and muscles)
glycerol (from lipolysis)
what is lipolysis
breakdown of triacylglycerols to glycerol and FFAs
what is lipogenesis
synthesis of triacylglycerols (storage in fat depots)
where does the cori cycle happen
muscle cells
STEPS for carbohydrate metabolism - Cori cycle
1) lactate produced by aerobic glycolysis of the muscle moves to the liver then the
glucose returns to muscle
2) muscles use O2 and glucose to make ATP (energy)
the availability of O2 for ETP becomes limited/decreases
3) the TCA cycle = inhibited > build up of pyruvate/pyruvic acid
glycolysis can still occur as no O2 is needed
4) more pyruvate is made by glycolysis > fermentation > lactate
liver
5) lactate is shuttled to liver where using lactate dehydrogenase becomes pyruvate
6) pyruvate undergoes gluconeogenesis and 6 ATP becomes glucose which can be
shuttled to muscle cells for use
