hemeandironquestions Flashcards
what does a small erythrocytes mean
problem with not enough cytoplasm most likely due to an iron deficiency anemia.
tell me about the hydroxyl radical
highly reactive and does loads of damage can be made from H2O2 from iron or copper
how is iron lost
no regulated way because its always bound to protein so lost when the cells containing it are lost like the intesitne and kidney cells that die off and are excreted. Or with blood loss. Or with intravascular hemolysis but this is pathological.
what is the distibution of iron in the body
80% is in the active forms hemoglobin myoglobin transferrin and cytochormes, and 20% in inactive forms ferritin and hemosiderin as a long term storage.
what are the gatekeepers for iron entry from the gut
enterocytes
what transporter in the enterocytes lets iron Fe2+ up
DMTI
how does iron Fe3+ get in
reduced by cytochome B to iron 2+ and then DMT1
how does Heme get into the body
the heme transporter takes it up and then it is transferred by ferritin for storage,
how does iron get from the enterocytes to the circulation
Ferroportin 1 will export the iron from ferritin to transferrin by making first into Fe3+ by hephaestin
what does hepcidin do
it regulates the activity of ferroportin 1 and thus regulates how much iron will enter the circulation.
how does iron get into the cells
trasferrin carrying Fe3+ wil bind to a receptor and this whole complex will be taken it and then the iron will be reduced to Fe2+ by importing H+ into the vesicle and will unbind transferrin and then DMT1 will export it from the vesicle to the cells cytoplasm.
what happends to ferritin over time
it will denature and become water insoluble, hard to mobilize and is a sign of iron overdose.
what is the main iron regulator and how does it work
hepcidin is the main regulator, so low hepcidin= high uptake of iron, and it also regulate the release of iron from macrophages.
what is HFE
an upstream regulator that will cause low hepcidin expression.
tell me about the regulation of intracelluar storage for a quick response
the RNA is already made but is bound to proteins in the cytoplasm, this protein will prevent translation. If iron is high in the cytoplasm it will bind to the Iron regulatory protein ACONITASE and this will free the RNA to be translated.
tell me about iron response elements
found on RNA of, ferritin free iron increases translation 5’, ALA synthase free iron will incraese translation 5’ edn, Trasferrin receptors here the IRE is found in the 3’ end and will repress the translation to lower the uptake.
tell me about serum iron concentration
it just tells you about total amount so if you have too much and its toxic but not about any specific stores of iron
tell me about total iron binding capacity or transferrin saturation
TIBC measure unoccupied transferrrin the higher the TIBC the lower the stores. So transferrin saturation measure occupied transferrin the higher the sat the higher the iron stores.
tell me about serum ferritin test
a fraction of ferritn is present in serum and best measure for body iron stores.
tell me about the red cell protoporphyrin
iron free precursor to heme the lower the iron stores the higher the protoporphyrin.
what are some causes of iron deficiency
chronic blood loss, chronic disease, poor dietary intake, intestinal parasites, malabsorptive disease like celiac
what does an iron deficiency lead to
anemia, mycrocytosis
what causes iron overload
blood transfusions, slow erythropoiesis renal failure, hereditary hemochromatosis type 1 up to 10 % of the population are carriers.
what do you look for in iron overload
high transferrin saturation and hemosiderin deposits
how does lead effect heme sythesis
PBG sythas or ALAL dehyratease, and ferrochelatse
what regulates the ALA sythase
regulated by HEME
what is acute intermittent porphyria AIP
caused by deficiency in porpoobilnogen daminase PBGD. ALA and PBG accumulate in the circulation giving urine dark red color can be life threatening and causes confusion and pain in the abdomin.
tell me about Porphyria cutanea tarda PCT
results for a deficiency of uroporphyrinogen decarbocylase, leads to a buildup of porphins can be detected in urin with a UV light
tell me about lead poisoning
lead inhibits ALA dehyrase and ferrochelatase, accumulation of ALA and heme precursors and causes sympotoms similar to the porphyrias.
