Heme Flashcards
how does heme synthesis start
ALA synthase is activated, synthesizes ALA from succinyl - CoA and glycine.
where is ALA synthase located
mitochondria
what happens to ALA after its made
gots to cytosol, where it turns into PBG from PBG synthase
what happens to PBG after it’s made
jointed to form uroporphyrinogen by uroporphyirogen synthase III
what is the committed step of heme synthesis
ALA synthase
what inhibits heme synthesis
heme
how does synthesis of p450 enzymes affect heme
consumes it and increases synthesis
in general what do problems in synthesis of heme lead to
incrase in ALA synthase activity
porphyrias
diseases of heme synthesis
what causes AIP
deficiency of porphobiliinogen deaminase
symptoms of AIP
urine gets a dark red color
confusion
sharp abodminal pain
what is PCT caused by
deficiency of uroporphyrinogen decarbosylase
symptoms of PCT
urine that emits pink gluorence under UV
photosensitivity of skin
what does lead inhibit
porphobilnogen synthase and ferrochelatase
symptoms of lead poisiong
simliar to porphyrias, prescne of lead adn heme precuros in urin
what is the half-life of RBCs
120 days
is bilirubin hydrophilic or hydrophobic
hydrophobic
where is bilirubin produced
spleen
how does bilirubin get to liber
binds to albumin
how is conjugated bilirubin secreted?
hepatocytes into bilirary capillaried and through gall duct
what is the compound that makes poo brown
urobilin
how do you get urobilin
spontaneous oxidation of urobilinogen
where does yellow color of urine come from
urobilins that were reabsorbed from gut
under normal conditions should you see bilirubin in the urine
no
is urobilin water solube?
yes
hyperbilirubinemia
serum bilirumb >1.5 mg/dL
kernitcterus
unconjuaged bilirubin crosses BBB and damages brain
what causes prehepatic jaundice
destruction of RBCs causes excess serum bilirubin that the liver can’t deal with.
in prehepatic jaundice what type of bilirubin is in the serum
unconjugated
example of prehepatic jaundice
neonatal physiological juandice
hemolytic disease
symptoms of hepatocellular jaundice
pale feces and urine
in hepatocellular jaundice waht type of bilirubin is in serum
unconjugated
what casues hepatocellular jaundice
hepatitis, or acetaminophen poising
symptoms of cholestatic jaundice (obstruction)
pale feces
intense urine
what type of bilirubin in tissues and urine in choelstatic jaundice
conjugated
when do you see markers of ALT and AST
hepatocellular jaundice
what is in the urine in hemolytic jaundice
no bilirunbin
