Describe and explain how the lungs are adapted to allow rapid exchange of oxygen between air in the alveoli and blood in the capillaries around them.

·         Many alveoli / alveoli walls folded provide a large surface area;

·         Many capillaries provide a large surface area;

·         (So) fast diffusion;

·         Alveoli or capillary walls / epithelium / lining are thin /

·         short distance between alveoli and blood;

·         Flattened / squamous epithelium;

·         (So) short diffusion distance / pathway;

·         (So) fast diffusion;

·         Ventilation / circulation;

·         Maintains a diffusion / concentration gradient; fast diffusion;