Lung Functions: Gas Exchange, pH Balance, Defense, and Voice

The lungs perform six vital functions:

1. Gas Exchange: Alveolar-capillary interface—O₂ in, CO₂ out (diffusion gradient).
2. Respiratory Control: Chemoreceptors (central/peripheral) sense pH, pCO₂, pO₂ → adjust rate/depth.
3. Voice Production: Airflow through adducted vocal folds → vibration → sound shaped by articulators.
4. Blood pH Regulation: CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻. Hyperventilation ↓ CO₂ → ↑ pH; hypoventilation opposite.
5. Air Filtration: Mucociliary escalator (cilia + mucus) traps particles → cough/swallow. Macrophages in alveoli.
6. Surfactant Production: Type II pneumocytes secrete dipalmitoylphosphatidylcholine → ↓ surface tension → prevents alveolar collapse (atelectasis).

Lung health = avoid smoking/vaping, minimize pollutants, exercise, vaccinate (flu, pneumococcal, COVID), treat sleep apnea.