How many alveoli are in an average adult human lung?

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Medical illustration of the human chest showing the lungs, diaphragm, ribs, trachea, bronchus, and bronchioles, with one lung cut away to reveal internal structures. — human respiratory system The lungs serve as the gas-exchanging organ for the process of respiration.

An average adult human lung contains approximately 480 million alveoli. These small, polyhedral air spaces are the primary sites for gas exchange within the respiratory system, where oxygen enters the blood and carbon dioxide is removed through the process of diffusion.12