Gas exchange

Let’s learn

Core knowledge: Efficient gas-exchange surfaces provide large surface area, short diffusion distance and a maintained concentration gradient.

Relate alveolar structures to rapid oxygen and carbon-dioxide exchange.

See it

Alveoli are numerous and have one-cell-thick moist walls. Dense capillaries and ventilation maintain gradients, so oxygen diffuses into blood rapidly.

Try it together

Annotate an alveolus-capillary diagram with structure → consequence → function statements.

Now you try

1. Why are alveolar walls thin? 2. How does blood flow maintain a gradient? 3. Explain one effect of emphysema.