BRAINCAKEEffective Gas Exchange Systems
An effective gas exchange system maximises the rate of diffusion described by Fick's law. Whatever the organism, efficient gas exchange surfaces share the same features.
1. A large surface area. Folding, branching or flattening gives a large surface area in a small space, such as the millions of alveoli in mammalian lungs, the filaments and lamellae of fish gills, and the network of tracheoles in insects.
2. A thin surface. The barrier between the medium and the blood is very thin, often one flat cell thick, giving a short diffusion distance.
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Key terms in this lesson
- fick's law
- The law stating that the rate of diffusion across a surface is proportional to its surface area and the concentration difference, and inversely proportional to its thickness.
More in Gas Exchange
- Gas Exchange in Small Organisms
- Surface Area to Volume Ratio
- Gas Exchange in Large Organisms
- Factors Affecting the Rate of Diffusion
- The Human Gas Exchange System
- Gas Exchange in the Alveoli
- Adaptations of the Human Gas Exchange System
- Breathing
All 23 lessons in Gas Exchange · All Edexcel AS-level Biology topics