Hem 4 - Erythropoiesis Flashcards
(30 cards)
When and where do the primitive blood cell progenitors appear? And where do the true hematopoietic stem cells come from And later migrate to?
The appear in the yolk sac at about 3 weeks. The true hematopoietic stem cells come from near the mesonephros and migrate to the liver.
Where is blood synthesized in the fetus?
[Young Liver Synthesizes Blood] hematopoiesis starts off in the Yolk sac from week 3 until about week 8. Liver and the Spleen; liver is the most important site of hematopoiesis thru fetal development. around week 28, the primary site of hematopoiesis is the Bone marrow.
What are the globin chains in the RBC of an Adult?
2 alpha-chains and 2 beta-chains.
What are the globin chains in the RBC of a fetus?
2 alpha-chains and 2 gamma chains.
What is special about gamma chains found in fetus RBC?
They have lower affinity for 2,3-DPG and a higher affinity for O2.
Where do we see and what is the structure of Hb A?
Found in 97% of normal hemoglobin. Structure is 2 alpha chains and 2 beta chains.
Where do we see and what is the structure of Hb A2?
Found in 2% of normal hemoglobin. Structure is 2 alpha and 2 delta.
Where do we see and what is the structure of Hb A1c?
Seen in poorly-controlled diabetes. Structure is 2 alpha and 2beta-glucose.
Where do we see and what is the structure of Hb F?
Found in fetal hemoglobin. Structure is 2 alpha, 2 gamma chians.
Where do we see and what is the structure of Hb Gower?
Found in embryonic hemoglobin. Structure is 2 zeta chains and 2 epsilon chains.
Where do we see and what is the structure of Hb S?
Found in Sickle cell hemoglobin. Structure is 2 alpha, 2 beta (single amino acid substitution from glutamine to valine In beta chain).
Where do we see and what is the structure of Hb C?
Found in Hemoglobin C disease. Structure is 2 alpha, 2 beta (glutamine has been changed for lysine in beta chain).
Where do we see and what is the structure of Hb Bart’s?
Seen in severe alpha-thalassemia. Structure is 4 gamma chains (no alpha chains).
Where do we see and what is the structure of Hb H?
Found in severe alpha-thalassemia. Structure is 4 beta chains. No alpha chains.
What is the rate limiting enzyme of heme synthesis?
Aminolevulinic acid synthase. Glycine and succinyl-CoA are the substrates. Vitamin B6 is a necessary co-factor.
What is the cause of acute intermittent porphyria And the symptoms?
Caused by deficiency of uroporphyrinogen-1-synthase. AKA porphobilinogen deaminase. Causes abdominal pain, port wine urine, and polyneuropathy and psychological disturbances. It can be precipitated by drugs (barbiturates, seizure drugs, rifampin, and metoclopramide).
What is the treatment for acute intermittent porphyria?
Treat by giving glucose and heme, which inhibit the ALA synthase.
What is the cause of Porphyria cutanea tarda and what are the symptoms?
Caused by Uroporphyrinogen decarboxylase. Causes blistering of the skin and photosensitivity, tea-colored urine, hypertrichosis, facial hyperpigmentation
Which type of porphyria is the most common?
Porphyria cutanea tarda.
Which three factors are associated w/ porphyria cutanea tarda?
Hepatitis C. Alcoholism. Elevation of LFTs.
What two things does lead poisoning affect in the heme synthesis pathway?
ALA dehydratase. Ferrochelatase.
What would inhibition of ferrochelatase cause in the RBCs?
RBCs will have increased levels of protoporphyrin.
What does lead poisoning cause?
Microcytic anemia (And basophilic stippling, and ringed sideroblastic anemia) and neurological manifestations; global encephalopathy w/ memory loss and delirium and mental deterioration, foot drop or wrist drop. Lead lines on the gingivae (Burton’s line) and metaphysis. Colicky abdominal pain and renal failure.
What is the treatment for lead poisoning?
EDTA or succimer in either kids or adults. Kids w/ severe toxicity and very high levels, give dimercaprol + succimer.7
