Red cell metabolism Flashcards
RBC functions
oxygen carriage + delivery
energy release
deoxygenated promote blood flow
Immune response (free radical release)
Intracellular buffer
K homeostasis (RBCs contain potassium)
Where does haem synthesis occur?
partly in the mitochondria and partly in the cytoplasm
(beginning + final step = mitochondrial, some intermediate steps = cytoplasmic)
What type of enzyme is ALA dehydratase?
-SH containing enzyme
[susceptible to inhibition by heavy metals, especially lead)
Porphyria acute attacks symptoms
unexplained abdominal pain
nausea, vomiting, constipation
neuropsychiatric symptoms
hyponatraemia
Porphyria acute attacks signs
PBG (and ALA) in urine
[porphobilinogen, ALA dehydratase]
What is porphyria?
group of disorders which result from abnormalities in the biosynthesis of haem
RBC lifespan
120 days
Where are old RBCs removed from circulation and degenerated?
spleen
Describe unconjugated bilirubin
fat-soluble
transported on proteins
taken into fatty tissue (Kernicterus)
[brain = fatty tissue]
[bilirubin should be conjugated]
Describe conjugated bilirubin
water-soluble
appears in urine
appears in faeces
Describe haemolytic jaundice
results in increased production of bilirubin
more bilirubin is conjugated and excreted than normally, but conjugation mechanism is overwhelmed, and an abnormally large amount of unconjugated bilirubin is found in the blood
may be caused by inability of hepatocytes to take up bilirubin from blood
as a result, unconjugated bilirubin accumulates
What is jaundice?
appearance of bilirubin in tissues = yellow discolouration of skin + sclera
Why should you beware of painless jaundice?
slowly evolving
continuous increase in bilirubin
no colic type symptoms
pancreatic cancer?
