Lecture Notes: Red Blood Cells

Introduction to Red Blood Cells

• Formation:
  • Formed in the bone marrow, the reddish material inside bones.
  • Blood stem cells in the bone marrow give rise to red blood cells.
  • Bone marrow can continuously divide due to the presence of telomerase, facilitating unlimited division.

Structure of Red Blood Cells

• Size:
  • Diameter: 7 micrometers.
  • Diameter matches the lumen of capillaries, enabling single-file movement for efficient oxygen delivery.
• Shape:
  • Biconcave disk shape.
  • The term 'biconcave' refers to the inward curvature on both sides of the cell.

Importance of Biconcave Shape

• Surface Area:
  • Increases total surface area for diffusion.
  • Higher surface area compared to normal or biconvex cells.
• Volume and Diffusion:
  • Lower volume than biconvex cells.
  • High surface area to volume ratio facilitates easier oxygen diffusion.
• Comparison of Ratios:
  • Example: Biconcave cell (5:1) vs. Biconvex cell (5:3).

Flexibility of Red Blood Cells

• Adaptivity:
  • Red blood cells can bend and change shape.
  • Flexibility allows cells to navigate through narrow capillaries, preventing clots.

Internal Structure

• Lack of Organelles:
  • No nucleus, rough ER, Golgi apparatus, mitochondria.
  • Space optimized for hemoglobin to maximize oxygen transport.

Summary of Key Adaptations

• Characteristics:
  • 7 micrometers in diameter.
  • Biconcave disk shape for better diffusion.
  • Flexibility to navigate capillaries.
  • Absence of organelles for hemoglobin accommodation.
• Explanation vs. Description:
  • Describe: Features like biconcave disk shape.
  • Explain: Higher surface area to volume ratio aids in oxygen diffusion.