Cell Specialization Lecture Notes

Introduction

• The lecture focuses on cell specialization and differentiation.
• Important for the High-Level (HL) curriculum.
• Examples of specialized cells are crucial for understanding specific functions.

Surface Area to Volume Ratio

• Cells need to maintain an optimal surface area to volume ratio for homeostasis.
• A high ratio implies a larger membrane area compared to the cell's volume.

Red Blood Cells (RBCs)

• Function: Carry and transport nutrients efficiently.
• Adaptation: Biconcave disc shape increases surface area to volume ratio.
  • Allows more space for nutrient transfer.
  • Shortens distance within cytoplasm.

Proximal Convoluted Tubule Cells

• Location: Kidneys.
• Function: Reabsorb nutrients from filtrate back into blood.
• Adaptation:
  • One cell thick layer for quick exchange.
  • Microvilli on the apical surface and invaginations on the basal surface increase surface area.

Lung Cells

• Alveoli: Small air sacs aiding gas exchange.
• Cell Types:
  • Type 1 Pneumocytes:
    • Wide and thin for efficient gas diffusion.
  • Type 2 Pneumocytes:
    • Cuboidal shape.
    • Produce surfactant to prevent alveolar collapse.

Muscle Cells

• Skeletal Muscle
  • Voluntary muscles, striated appearance.
  • Long cells with many nuclei.
  • Formed by fusion of multiple embryonic cells.
• Cardiac Muscle
  • Found in heart, shorter cells with one nucleus.
  • Cells connected by intercalated discs for synchronized contraction.

Gametes (Sperm and Egg Cells)

• Egg Cells
  • Large, contain organelles for zygote development.
  • Stationary, moved passively.
  • Sperm entry alters membrane to prevent further entry.
• Sperm Cells
  • Small, minimal cytoplasm.
  • Tail packed with mitochondria for motility.
  • Enzymes on the head to penetrate egg layers.

Conclusion

• Specialized cells perform distinct functions critical for life processes.
• Understanding specific adaptations helps in grasping their roles in the body.