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Structure of mature red blood cells Mature Erythrocyte devoid of Nucleus, Mitochondria & Endoplasmic reticulum. Cell membrane elasticity. Passive in nature. Utilize anaerobic respiration. Contain Hemoglobin & enzymes.
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Fate of Red Blood Cells
Dr. Wasif Haq
Structure of mature red blood cells• Mature Erythrocyte devoid of Nucleus,
Mitochondria & Endoplasmic reticulum.• Cell membrane elasticity.• Passive in nature.• Utilize anaerobic respiration.• Contain Hemoglobin & enzymes.
Function of enzymes in erythrocytes
• Membrane flexibility.• Ions transportation.• Iron in Ferrous form, not in Ferric form.• Protein oxidation in red blood cells prevented.
Eventual fate of Red blood cells
• Approx life span=100-120 days.• Self destruction (Eryptosis)• Eryptosis vs Apoptosis?• Spleen=Grave yard of red blood cells.• A non-functional or severely damaged red
blood cell may be removed earlier.
Mechanism of Eryptosis
• Triggered by glucose depletion, oxidative stress, osmotic shock, bacterial cell wall components, drugs & certain metal ions.
• Membrane fragility increases=Slowing of metabolism, deficiency of new enzymes & energy.
• Cell membrane blebbing, cell shrinkage & Phosphatidylserine activation, attracting macrophages.
• Rupture during circulation & in pulp of spleen.
Eryptosis- Influencing factors
• Eryptosis rate= Erythropoiesis rate. • Significance?• Role of Erythropoietin?• Increased Eryptosis: Sepsis, malaria, sickle cell
anemia, Iron deficiency, B-Thalessemia, Lead & Mercury intoxication.
• Decreased Eryptosis: Urea, Catecholamines & Nitric Oxide.
Fate of Hemoglobin• Hemoglobin released in circulation.• Phagocytized by macrophages in body, especially
liver, spleen & bone marrow.• Hemolyzed hemoglobin bound with plasma protein
called haptoglobin which prevents its excretion.• Iron released by Macrophages which is carried by
transferrin.• Porphyrin converted to bilirubin. • Iron may be recirculated or transported to liver for
storage in form of Ferritin.
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