Alveoli
Biology: Cambridge International GCSE Supplement, topic 11.1.3
Alveoli
The alveoli are tiny air sacs in the lungs. Oxygen and carbon dioxide move between the air and blood by diffusion in the alveoli. Alveoli are adapted to be very efficient at exchanging substances:
Large surface area
- Alveoli have a large surface area.
Surrounded by capillaries
- Alveoli are surrounded by a network of capillaries and so:
- they have a rich oxygen supply.
- the distance for gases to diffuse is small.
Test yourself on Alveoli
How do oxygen and carbon dioxide move between the air and blood?
How are alveoli adapted for their function?
The alveoli in your lungs have a larger surface area to increase the rate of diffusion of oxygen and carbon dioxide. What else can increase the rate of diffusion?
Which of the following are true of the alveoli in the lungs?