Lecture on Red Blood Cells

Introduction to Red Blood Cells

• Origin: Formed in the bone marrow, which is located within bones.
  • Bone marrow contains blood stem cells.
• Function of Bone Marrow: Produces blood cells, not just for protection or support.

Stem Cells

• Definition: Cells that can divide without limits, due to enzyme telomerase.
• Blood Stem Cells: Can specialize into red blood cells.

Structure of Red Blood Cells

• Diameter: Approximately 7 micrometers.
  • Corresponds to the lumen of capillaries, facilitating single-line movement and oxygen delivery.
• Shape: Biconcave disk.
  • Meaning: Concave (curved inwards) on both sides.

Importance of Biconcave Shape

• Comparison with Other Cells:
  • Normal Cell: Regular surface area.
  • Biconcave Cell: Increased surface area due to inward curvature.
  • Biconvex Cell: Increased surface area due to outward curvature.
• Surface Area to Volume Ratio:
  • Optimal for diffusion when surface area is high and volume is low.
  • Biconcave cells achieve a higher ratio, facilitating easier oxygen diffusion.

Flexibility of Red Blood Cells

• Ability to Bend: Changes shape to navigate narrow capillaries.
  • Prevents blood clots by allowing passage through tight spaces.
• Restoration: Returns to original shape post-deformation.

Internal Composition of Red Blood Cells

• Lack of Organelles: No nucleus, ER, ribosomes, mitochondria.
  • Purpose: More space for hemoglobin, increasing oxygen transport capacity.

Key Features to Remember

• Diameter of 7 micrometers.
• Biconcave disk shape.
• Flexibility.
• Lack of nucleus and other organelles.

Explanation vs. Description

• Description: Identifying features like biconcave shape.
• Explanation: Understanding the purpose, such as higher surface area to volume ratio for oxygen diffusion.