Pulmonary acinus

Last revised by Liz Silverstone on 7 Mar 2024

The pulmonary acinus is an anatomical unit of lung supplied by a first order respiratory bronchiole, 4-8 mm in diameter. Each secondary pulmonary lobule usually contains 3-25 acini, and adjacent acini are separated by incomplete intralobular septa.

Clinical importance

The component respiratory bronchioles, alveolar ducts and alveoli take part in gas exchange 2.

Related pathology

In disease, the acini may be filled with fluid and cells and may appear as small ill-defined “air space nodules”.

See also

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