The largest lung subunit in which all airways participate in gas exchange, and it is composed of the parenchyma of the respiratory bronchioles, alveolar ducts, and alveoli. [ http://www.ncbi.nlm.nih.gov/pubmed/2014492 http://en.wikipedia.org/wiki/Acinus#The_Lungs MP:0010911 http://www.ncbi.nlm.nih.gov/pubmed/3382030 ]

Synonyms: acinus pulmonaris arbor alveolaris pulmonary acini

This is just here as a test because I lose it