Hema 1: Erythrocyte Production and Destruction

• What is the primary function of erythrocytes?

  To carry oxygen from lungs to tissues
• What are the three nomenclatures for erythroid precursors?


  • Burst-forming unit-erythroid (BFU-E)
  • Colony-forming unit-erythroid (CFU-E)
• What happens to erythroid precursors as they mature?

  They undergo general trends affecting their appearance
• What are the stages of erythroid maturation?

  1. Pronormoblast (Rubriblast)
  2. Basophilic Normoblast (Prorubricyte)
  3. Polychromatic Normoblast (Rubricyte)
  4. Orthochromic Normoblast (Metarubricyte)
  5. Erythrocyte
• What is the N:C ratio of a Pronormoblast?

  1. 1
• Why does the Pronormoblast appear dark blue?

  Due to RNA and ribosomes concentration
• What is the N:C ratio of a Basophilic Normoblast?

  1. 1
• What color does the cytoplasm of a Basophilic Normoblast appear?

  Deeper, richer blue
• What is the last stage of erythroid maturation capable of mitosis?

  Polychromatic Normoblast (Rubricyte)
• What is the N:C ratio of a Polychromatic Normoblast?

  Decreases from 4:1 to 1:1
• Why does the Polychromatic Normoblast appear pink?

  Due to hemoglobin accumulation
• What is the characteristic of a Polychromatic Erythrocyte or Reticulocyte?

  Absence of nucleus
• What gives the Polychromatic Erythrocyte its bluish tinge?

  Residual ribosomes and RNA
• What is the N:C ratio of an Orthochromic Normoblast?

  Approximately 1:2
• What color does the Orthochromic Normoblast exhibit?


  Increase in salmon pink color
• What is the diameter range of an erythrocyte?


  6 to 8 µm
• How does an erythrocyte appear on a Wright-stained blood film?

  Salmon-pink stained cell with central pallor
• What is erythrokinetics?

  • Dynamics of RBC production and destruction
• What is hypoxia in relation to red blood cell production?


  Stimulus for increased RBC production
• Where is hypoxia detected in the body?

  By peritubular fibroblasts in the kidney
• What does EPO trigger in response to hypoxia?

  Release of RBCs from the bone marrow
• What are the three major effects of EPO?

  1. Early release of reticulocytes
• What is the reference value for EPO measurement?

  10 to 30 U/L
• What are therapeutic uses of recombinant EPO?


  • Therapy for certain anemias
  • Autologous blood donation
  • After bone marrow transplant
• What other stimuli can promote erythropoiesis?

  Testosterone, pituitary, and thyroid hormones
• Why can't mature erythrocytes generate new proteins?

  They are nonnucleated cells
• What is the lifespan of red blood cells?

  90 to 120 days
• What are the types of hemolysis?

  • Macrophage-mediated hemolysis (extravascular)
  • Mechanical hemolysis (intravascular)
• What happens to aged RBCs in the spleen?

  They succumb to stress in the cords of Billroth
• What occurs during macrophage-mediated hemolysis?

  Macrophages ingest abnormal RBC shapes
• What is fragmentation or intravascular hemolysis?

  RBC rupture from mechanical or traumatic stress
• What are the differences between macrophage-mediated hemolysis and mechanical hemolysis?

  • Macrophage-mediated: Involves ingestion of aged RBCs
  • Mechanical: Involves rupture from stress