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20 Cards in this Set
- Front
- Back
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What are four causes of ineffective Erythropoiesis in BM? |
Megaloblastic (B12 / folate )Defective DNA synthesisis
Sideroblastic - defective haem synthesis Thalassaemic - a/b chain deletion, defective globulin synth Myelodysplastic Syndromes- Qualitative abnormalities of all cell lines |
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What is PB haemaolytic aneamia? |
Increased rate of RBC destruction
Rate of destruction exceeds production |
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How does rbc turnover occur? |
rbc survival - 120 days
Macrophages of RE system remove rbcs in spleen RE system is extravascular so (90%) rbc occurs without Hb release into circulation |
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What is the site of extravascular haemolysis?
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Red pulp in the spleen
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How is Hb catabolised?
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Globlin degraded to aas
Iron recycled (RE system) Porphyrin moiety is metabolised to bilirubin - excretred in the liver |
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What is the fate of intravascular Hb? |
Free Hb (a2b2 tetramers) to dimer
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What are lab signs of haemolysis? |
Indirect Bilirubin - as 80% of bilirubin production comes from Hb degradation |
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Lab signs of Intravascular haemolysis |
v. high LDH Absent heptoglobin Raised bilirubin Urine haemoglobinaemia - free Hb in plasma haemoglobinuria - free Hb in urine haemosiderin- lots of Fe recycled |
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Lab signs of Intravascular haemolysis |
No haptoglobin |
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What shapes would be seen in abnormal hameolysis? |
Spherocytes Schistocytes- fragments Helmet cells,Bite Cells, Blister Cells |
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What might rbcs also contain to indicate abnormal hameolysis? |
Formation of red cell inclusion bodies DNA,RNA,Haemoglobin |
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Summary of lab signs of haemolysis? |
Extravascular - Increased bilirubin Low serum heptoglobin Increased LDH RBC morphology - abnormal shape, sometimes inclusion bodies ALWAYS - increased retic count |
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What are three causes of rbc destruction? |
rbc trauma, dysfunction and ineffective erythropoeisis |
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What are types of rbc trauma? |
mechanical, burns, chemical, microangiopathic |
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What is the rbc energy source? |
Glucose
Catabolised to pyruvate and lactate |
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Does rbc carry or consume O2? |
Only carriers |
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What is the name of the pathway which catabolises glucose to pyruvate and lactate? |
Embden-Myerhoff Pathway- anaerobic glycolysis
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What is the energy used for? |
Membrane ATPase Na pump 1ATP moves 3Na ions out and 2K ions into rbc |
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What is the result of pyruvate deficiency? |
Less ATP produced
2,3-DPG builds up - alters Hb conformation via b-globulin chains (O2 right shift - compensated anemia) Na pump does not work so water pulled along with Na into cells. Intracelllular water accumulates |
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How do PK deficient rbcs compensate? |
2,3-DPG build up - O2 right shift - compensated anemia Retics in PK deficiency Oxidative phosphorylation in retics Mi (so require good O2 supply) |
