Alveolus

Definition

An alveolus is a tiny, balloon-like structure in the lungs where gas exchange occurs, allowing oxygen to enter the blood and carbon dioxide to be expelled. It is the endpoint of the respiratory tract where actual breathing takes place.

Related terms

Gas exchange: The process by which oxygen is absorbed into the body from the lungs and carbon dioxide is expelled out of the body through the lungs.

Bronchioles:

The small tubes that branch off from the bronchi and lead directly to the alveoli in the lungs.

Capillaries:

Tiny blood vessels that surround the alveoli, through which gas exchange between air and blood occurs