Additional defence mechanisms

• Sputum:

  • acts as flypaper
  • traps foreign bodies in mucus layer
  • cilia then sweeps the mucus up to the mouth
• Cough reflex:

  • Carina (bifurcation of trachea into right and left main bronchus) has lots of nerve endings around it
  • a build up of mucus around the carina will trigger person to cough
• Wandering macrophages:

  • Another lung defence mechanism
  • At alveolar level
  • Keep the alveolar surfaces sterile
  • Dead macrophages swept up by cilia