This lecture by the instructor delves into the intricate phenomena of airflow and aerosol transport in the deep lungs, exploring the anatomy of the respiratory organ, the structure of the airways, and the Reynolds number cascade. The presentation covers topics such as the morphology of the pulmonary acinus, alveolar flow patterns, and the role of inertia in flow topology. It also discusses the acinar-on-chip model, in silico simulations, and aerosol deposition in the acinus. The lecture concludes with insights on irreversible mixing, particle tracking, and the impact of scales on tracer aerosols, providing a comprehensive overview of the complexities involved in studying lung ventilation and aerosol dynamics.