Why Cells Are Small: The Physical Constraints of Surface Area and Diffusion

Summary

This article explores why cells are typically small, focusing on two key physical constraints: surface area-to-volume ratio and diffusion limits. It explains that as a cell grows, its volume increases faster than its surface area, making it difficult to exchange nutrients and waste efficiently. Diffusion, which moves molecules passively, becomes too slow over larger distances. These constraints explain why most human cells are microscopic, though specialized cells like oocytes can be much larger due to unique adaptations.