Introduction: primary fxn of pulmonary system, body enhances rate gas exchange, study table of abbreviations, gas exchange (o2 uptake and co2 removal @ appropriate fxning rates) Pulmonary structure and fxn: anatomy of the respiratory system, consists of nose, pharynx, larynx, trachea, bronchi, and lungs, trachea keep larger airways open, higher order bronchi, almost completely surrounded by rings of cartilage. Cartilage helps: as bronchi gets smaller, cartilage gradually replaced by sm. Designed to enhance surface area for diffusion. About 23 bifurcations from trachea to alveoli. Bronchi primary, secondary, tertiary bronchi terminal and respiratory bronchioles alveolar ducts alveoli. 300 million alveoli = 1 tennis court of sa. Each alveolus enveloped by a bed of capillaries = incr sa. 80% alveolar wall available for gas exchange when all caps are open. Only one rbc can fit through at a time. O2 diffusion distance minimized: thickness reduction: Alveoli is 1 layer of epithelial tissue thick.