Cell Size & Surface Area-to-Volume Ratio

• Cell Size as an Aspect of Specialization


  Cell size varies greatly among different cell types, reflecting their specialized functions. Let's explore the range of cell sizes in humans:

  1. Gametes
  2. Blood Cells
  3. Neurons
  4. Striated Muscle Fibres
• Gametes


  • Male gamete (sperm): ~3-4 μm in diameter (head)
  • Female gamete (egg): ~100 μm in diameter
• Blood Cells


  • Red blood cell: ~7-8 μm in diameter
  • White blood cell: ~10-30 μm in diameter
• Neurons

  • Cell body: ~4-100 μm in diameter
  • Axon length: up to 1 meter
• Striated Muscle Fibres


  • Diameter: ~10-100 μm
  • Length: up to 30 cm
• Sperm cells are tiny to be mobile and penetrate the egg, while egg cells are large to contain nutrients for the developing embryo. Neurons have long axons to transmit signals over large distances in the body.
• Surface Area-to-Volume Ratios and Constraints on Cell Size

  The surface area-to-volume ratio (SA:V) is a crucial factor in determining cell size. As a cell grows, its volume increases faster than its surface area, which can limit the cell's ability to exchange materials with its environment.