| pubmed-article:9526907 | pubmed:abstractText | The upper airways--the nose, pharynx, and mouth--lead through the larynx and into the tracheobronchial tree of the lung (the lower airways). This cavernous void in the upper airways transports external air to the alveolar sacs, in the distal segments of the tracheobronchial tree. Oxygen is absorbed from the alveolar sacs and carbon dioxide is released. Yet, under adverse physiologic conditions such as allergic or nonallergic rhinitis, sinusitis, and bronchitis, obstruction of the upper and lower airways occurs and leads to sneezing, rhinitis, and bronchospasm. The simultaneous occurrence of upper airways disease and asthma is addressed in this review. | lld:pubmed |
