RBC Life Span and Circulation

• Red blood cells lose organelles after time, only retaining extensive cytoskeleton
• Without mitochondria, red blood cells obtain energy only by anaerobic metabolism so rely on glucose from surrounding plasma
• Red blood cells cannot replace damaged enzymes or structural proteins because there is no nucleus
• A single trip through the cardiovascular system for the RBC takes less than 30 seconds
• In one trip, the red blood cell

  • stack into a rouleau
  • contort and squeeze through capillaries
  • join other RBCs in a rush back to the heart for another trip
• Red blood cells last about 120 days
• Either plasma membrane ruptures or phagocytic cells detect and destroy the aging cell