Biology / Unit 13 Bio 3143 short lesson, about 20 seconds
Gas Exchange Surface Requirements
Captions available
The idea
An effective gas-exchange surface is thin, moist, and large relative to body size, since diffusion works only across short wet distances and exchange scales with area.
In practice
Lung alveoli multiply surface area through millions of small sacs rather than one large chamber.
Where people slip
A dry surface stops working — gases must dissolve in moisture before diffusing across it.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Something wrong in this lesson? Flag it · Sources for Biology