Adaptations of the Alveolus (WJEC GCSE Biology)

The Alveolus

• The lungs are the gas exchange surface in humans

  • They are adapted to maximise the exchange of gas by diffusion

• Inside the lungs there are many air-filled structures called alveoli

  • Alveoli are found at the end of the bronchioles

    • They consist of many individual sacs, each of which is called an alveolus

    • Each alveolus has a single-celled wall with a moist lining

  • The alveoli are surrounded by a network of capillaries containing red blood cells and plasma

    • Oxygen diffuses into the blood from the alveoli

    • Carbon dioxide diffuses out of the blood into the alveoli

Alveoli structure diagram

Alveoli contain many sac-like structures each of which is a single alveolus