Heme Catabolism Flashcards
How much Hb do we turn over per day
6 grams
how many red blood cells turnover per hour
100-200 million
what is the whole point of the heme catabolism pathway?
To solubilise the hydrophobic heme ring so that it can be excreted.
What is unconjugated BR
pre liver BR
conjugated BR
post liver BR
Which form of BR is soluble?
the conjugated form of BR
what is the daily BR formation in adults?
250-350 mg
Why are new born babies at higher risk of hyperbilirubinaemia neuro damage?
Their blood brain barrier is not yet fully developed and the BR that is unconjugated BR can easily get across to the brain as it is lipid soluble.
What would be a neurotoxic concentration of BR in a baby?
25 mg per 100ml or more
How does BR get into tissues from the blood serum?
diffusion
what are the three main reasons for jaundice in babies?
babies are getting rid of fetal red blood cells and replacing them with adult
fetal blood cells dont last as long
and lastly the liver enzymes the glucuronyltransferases are not yet fully functional leading to delaying of the conjugation of bilirubin slowing down the processing system.
what are some other causes of jaundice?
hyperthyroidism, prematurity of the new born, blood group incompatibility
what is crigler najer syndrome?
autosomal recessive trait resulting in absense of UDP glucuronyltransferase in type 1 - fatal
or resulting in defecting glucuronyltransferase so that only the 2nd sugar is added to BR this is treatable with phenobarbital
why would you get build up of conjugated BR
due to issues with the liver or a blockage of the bile duct
what happens to excess conjugated BR?
spills into the urine but makes it brown as conjugated BR is soluble
