Bilirubin Pathways Flashcards
bilirubin is an open chain called?
a tetrapyrrole rings
bilirubin breakdown of blood usually where?
spleen
Macrophages break form RBCs, then what?
into haem>biliverdin>free bilirubin
colour of bilirubin?
yellow
colour of biliverdin?
green
some double bonds in bilirubin isomerize when what? what does that do to bilirubin?
exposed to light = more soluble
When use phototherapy for bilirubin?
jaundiced newborns
2 forms of bilirubin?
conjugated and unconjugated
bilirubin usually excreted as?
conjugated (glucuronide) in bile
high bilirubin in newborns?
neurotoxic
RBCs stimulated by?
EPO
erythropoietin
how many RBCs made a die per second?
2 million
future RBCs leave the bone marrow as what? how long to mature to RBCs?
reticulocytes mature in a day
how long to create RBCs from stems?
7 days
RBCs last?
~120 days
what is met-haemoglobin?
Fe3+ that doesn’t bind O2 well
What is in white pulp and red pulp in spleen?
White pulp: T/B cells
Red pulp: blood vessels to remove old RBCs via macrophages
Mononuclear phagocyte is precursor to?
macrophage
Are there Mononuclear phagocytes in the liver?
yes. the Kupffer cells help out
what does the white pulp in spleen do?
opsonizes old RBCs to help with recognition by macrophages
aged RBCs lose what on their surface?
neuraminic/sialic acid from glycophorin
3 big factors for haemolysis?
strepto/enterococcus
parasitic: Malaria
congenital/genetic/autoimmune
What is Haptoglobin?
plasma protein that binds haemoglobin of RBCs that die away from spleen, allows macrophages to remove
Haptoglobin looks like?
trypsin
what carried haem (not Haemoglobin) to liver?
hemopexin recycles the iron
4 consequences of haemolysis
unconjugated bilirubin = jaundice
increased stercobilin
gall stones
reticulocytosis
Fe2+ carried by?
transferrin
Haem oxygenase produces?
biliverdin
How is biliverdin produces from Haem?
via haem oxygenase
Bruises: what happens at? 1-2 days 5-10 days 10-14 days >14 days
1-2 days: blue, purple black: deoxy/met-Hb
5-10 days: green/yellow = biliverdin
10-14 days: yellow/brown = bilirubin
>14 days : fades away
serum albumin binds what?
HIGHLY hydrophobic bilirubin
what converts bilirubin to conjugated bilirubin?
bilirubin UDP glucuronyltransferase
whats the difference between conjugated and unconjugated bilirubin?
conjugated is soluble
defect in bilirubin UDP glucuronyltransferase leads to what disease?
Crigler-Najjar disease
what actively pumps bilirubin diglucuronide into canaliculi?
cMOAT or MRP2
what is Crigler-Najjar disease?
defect in bilirubin UDP glucuronyltransferase
What is Dubin Johnson syndrome? prognosis?
defect in cMOAT
asymptomatic, no Rx necessary
Crigler-Najjar disease symptoms?
persistent jaundice
kernicterus
What is kernicterus?
bilirubin in brain
Crigler-Najjar disease initial and subsequent treatment?
initially: phototherapy 10-12 hr/day
subsequently: liver transplant
How much bile is recycled?
95% in terminal ileum
what are bile pigments?
bilirubin diglucuronide
what are bile salts?what do they do?
detergent derivatives of cholesterol
emulsify fats
90% of urobilinogen in faeces, 10% goes where?
10% back into portal vein
9% back to biliary system
1% into kidney and into urine = yellow pee
Why does old pee look more yellow?
+++ oxidized urobilinogen
What converts bilirubin diglucoruronide to sterco and urobilinogen?
microbial enzymes
