One cubic millimeter of lung tissue contains around 170 alveoli. Human lungs have a surface area of roughly 70 square meters.

When a human breathes in, their chest muscles move ... it passes through smaller and smaller tubes and ends up in tiny air sacs called alveoli. Oxygen passes through the walls of the alveoli ...

These end in microscopic air sacs called alveoli. The process of ventilation as a series of changes in pressure within the thorax can be modelled using the bell jar model. Parts of the model ...