The Lungs

The effectiveness of an exchange surface can be increased by:

- Having a large surface area

- Having a thin membrane - provides a short diffusion path

- Having an efficient blood supply (in animals and humans) to move the diffusing substances away, and to maintain a concentration gradient.

- Being ventilated (in humans and animals) to maintain steep concentration gradients.

- Having a moist surface

- Having a partially permeable membrane.

Lungs are specially adapted to make gas exchange more efficient - they are made of clusters of alvioli.

- These tiny air sacs give the lungs a large surface area, which is important for the most effective diffusion of oxygen and carbon dioxide.

- They also have a rich blood supply, which maintains a concentration gradient in both directions.

- As a result, gas exchange takes place along the steepest concentration…