1. Fate of Red Blood Cells
Dr. Wasif Haq

2. 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.

3. Function of enzymes in erythrocytes
Membrane flexibility.
Ions transportation.
Iron in Ferrous form, not in Ferric form.
Protein oxidation in red blood cells prevented.

4. Eventual fate of Red blood cells
Approx life span= 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.

6. 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.

7. 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.

9. 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.