Alveoli are an important part of the respiratory system whose function it is to exchange oxygen and carbon dioxide molecules to and from the bloodstream. These tiny, balloon-shaped air sacs sit at the very end of the respiratory tree and are arranged in clusters throughout the lungs.


Alveoli are tiny balloon shaped structures and are the smallest passageway in the respiratory system. The alveoli are very thin, allowing the relatively easy passage of oxygen and carbon dioxide (CO2) between the alveoli and blood vessels called capillaries.

Cells of the Alveoli 

The alveoli are made up of two different types of cells that have different functions:

  • Type I pneumocytes are the cells that are responsible for the exchange of oxygen and carbon dioxide.
  • Type II pneumocytes perform two important functions. They are responsible for repairing damage to the alveolar lining and also secrete surfactant.
Share This Post
How your heart works
How to stop a child from choking