The respiratory bronchioles lead into alveolar ducts which are deeply lined with alveoli. The branching process forms the bronchi, bronchioles, and ultimately the alveoli. Each duct opens into five or six alveolar sacs into which clusters of alveoli open. This process occurs in the pulmonary capillaries adjacent to the alveoli of the lungs. Avian lungs do not have alveoli as mammalian lungs do. Air is briefly stored inside small sacs known as alveoli (sing. Consolidation occurs through accumulation of inflammatory cellular exudate in the alveoli and adjoining ducts. The anti-GBM antibodies attack the alveoli and glomeruli basement membranes. Oxygen passively diffuses in the lung alveoli according to a pressure gradient. Fine dust particles are small enough to penetrate deep into the lung alveoli. The surrounding alveoli and pulmonary interstitium remain relatively normal. This is possible by increasing surfactant which coats the alveoli in the lungs for re-inflation. In the alveoli, macrophages ingest these microconidia. Tinier particles deposit more nicotine in the alveoli. It is also found in other locations, including the alveoli of the lungs.