The lung's "quiet zone".
D000367:Age Factors; D000403:Airway Resistance; D001249:Asthma / Q000503:physiopathology*; D001980:Bronchi / Q000503:physiopathology; D001991:Bronchitis / Q000503:physiopathology*; D002648:Child; D006801:Humans; D008168:Lung / Q000033:anatomy & histology / Q000254:growth & development; D012119:Respiration; D014132:Trachea / Q000503:physiopathology