Red blood cell

From IKE

Contents 1 Basics 2 Life cycle 3 Erythropoiesis 4 Anemia 5 Resources

Basics

• Red blood cells have a biconcave disc shape
  • This provides them the flexibility to negotiate the microcirculation
  • It also maximizes surface area for gas exchange
• The primary carriers of gases for cellular respiration
• Carry:
  • Oxygen
  • Carbon dioxide
  • Nitric oxide
• These gases are bound to hemoglobin

Life cycle

• Born in the marrow as a stem cell
  • This is a common predecessor for both white and red blood cells
• Stem cells differentiate (under the influence of erythropoietin) into:
  • erythroblasts, normoblasts, reticulocytes, and finally erythrocytes.
• During this progression:
  • size decreases
  • mitotic competence is lost
  • the size of the nucleus decreases (and it disappears completely)
  • Mitochondria and ribosomes are still present in reticulocytes, but are absent in mature red blood cells
• Generate energy through the glycolytic and phosphogluconate pathways
• Biconcave in appearance
• Exist in circulation for ~120 days
• Eventually removed by mononuclear phagocyte system
  • product of this catabolism is iron and amino acids (reutilized)
  • another product is bilirubin, which is excreted in bile

• A mature red blood cell has no nucleus, mitochondria, or ribosomes, and uses the glycolytic and phosphogluconate pathways for metabolic energy

Erythropoiesis

• See Hematopoiesis
• The normal life span of a red blood cell is 120 days
• 1% of the RBC pool is replaced daily
• Production is increased in response to decreased tissue oxygenation
• The major growth factor is erythropoietin
• produced by peritubular cells in the kidney

Anemia

• See Anemia

Resources

• Quarter 3 Biochemistry Lecture notes (PDF)