Lungs (2)

    Cards (6)

    • Approx. 300 million alveoli
    • Alveoli
      • Lined with lipoprotein (surfactant) which is a mix of phospholipids and protein
      • Contain epithelial cells
      • Type 1 alveolar cells have thin cell walls and are for gas exchange
      • Type 2 alveolar cells secrete surfactant and have microvilli
    • Alveolar surfactant

      Lowers surface tension at the air/liquid interface
    • Air movement into lungs
      1. Pressure changes
      2. Pressure is the amount of force created by movement and collision of the gas molecules
      3. Flow = pressure difference / resistance
      4. Pressure difference = atm pressure – alv pressure
    • Inhalation
      Always active
    • Exhalation
      1. Can be active or passive
      2. Lungs naturally recoil so exhalation restores the lungs to their resting position
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