Hematology I 501301 The Red Cell II: Metabolism

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Hematology I (501301) The Red Cell II
Metabolism Function?????? ???????

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Erythrocyte Metabolism

• Create ATP
• RBCs have no nucleus no organelles
• K high, Na low Ca very low
• Membrane asymmetry integrity

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Erythrocyte Metabolism (Cont.)

• Deformability RBC volume
• Hb function
• Reducing agents

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Glycolysis

• Glucose
• Anaerobic
• ATP
• Lactate CO2

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Glycolytic Pathway

• Embden-Myerhof pathway
• Hexose-monophosphate shunt
• Methemoglobin reductase pathway
• Rapoport-Leubering shunt

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Embden-Myerhof Pathway

• 90-95 of intracellular glucose
• RBCs have no glycogen
• Glucose (free-energy diffusion)
• Na-K ATPase pump
• Ca-Mg ATPase pump

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Hexose-Monophosphate Shunt

• 5 of intracellular glucose
• NADPH
• GSH
• H2O2

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Methemoglobin reductase Pathway

• Protect Fe (Ferrous form)
• Prevent oxidation to Fe (Ferric form)
• Methemoglobin reductase NADH
• Oxidant drugs foods

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Rapoport-Leubering Shunt

• Bypass 3-phosphoglycerate (3-PG) ATP
• Produce 2,3-di-phosphoglycerate (2,3-DPG) instead
• 2,3-DPG binds to DeoxyHb
• Release O2

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Erythrocyte Kinetics

• Production
• Destruction
• Hypoxia (low O2)
• Erythropoietin (Epo)
• Reticulocytes
• New born

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Erythrocyte Kinetics (Cont.)

• Anemia
• Malnutrition
• Iron Folate Deficiency
• Autoimmune Diseases
• Hemolysis
• Malignancy
• Intestinal Parasites

• Erythrocytosis
• Relative (Exercise)
• Absolute
• Primary (Polycytemia vera Erythroleukemia M6)
• Secondary (Pulmonary disorders)

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Erythropoietin (Epo.)

• Glycoprotein (Thermostable)
• 34 kDa
• Kidney ( Liver)
• CFU-E -gt Orthochromatic Normoblast
• Hypoxia
• Speed up Erythropoiesis
• Stress Reticulocytes

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Erythrocyte Function

• Hb
• O2 CO2 Transportation
• Hb-O2 Affinity
• pO2 pH H pCO2 2,3-DPG
• Temperature

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Hb-O2 Dissociation Curve

• Sigmoid Shape
• F8 Histidine Porpyrin Ring
• Alpha-Beta Dimer
• Cooperative Binding

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Hb-O2 Dissociation Curve
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Shift of Hb-O2 Dissociation Curve
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CO2 Transportation
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CO2 Transportation

• Direct Dissolve (15-18)
• Bicarbonate (70)
• Cabamino Hemoglobin (13-15)

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Bicarbonate

• Histidine residues (50)
• Plasma Protein Phosphate Buffer (10)
• Bohr Effect

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Bohr Effect

• 1. CA
• H2O CO2 -----gt H2CO3
• 2. H2CO3 ----gt H HCO3-
• 3. HHb O2 -----gt Hb (O2) H
• (Tense state) (Relax state)

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Erthrocyte Destruction

• Extravascular Hemolysis (major)
• Intravascular Hemolysis (minor)

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Extravascular Hemolysis
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Intravascular Hemolysis
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References
1. Harmening, D.H., et al., Clinical hematology
and fundamental of hemostasis, 3rd Ed, F.A. Davis
Company, Philadelphia, 1997. 2. McKenzie, S.B.,
et al., Text book of hematology, 2nd Ed, Williams
Wilkins, A Waverly Company, Baltimore,1995.