Lower Airway

• Function: exchange of oxygen & carbon dioxide
• Located from fourth cervical vertebrae to the Xiphoid process & from glottic opening to pulmonary capillary membrane
• Structures: trachea, bronchi, bronchioles, alveoli, lungs
• Trachea: splits at the carina into right & left bronchi - lined with mucous cells & beta-2-receptors (dilate)
• Bronchi:

  • Right mainstem bronchi has a lesser angle (where foreign bodies/ET tubes get displaced)
  • Mainstem enter lungs at hilum
• Bronchioles: The smaller tubes that branch off the bronchi - branch into alveolar ducts
• Alveoli: "grape-like" cluster of air sacs in lungs that are responsible for gas exchange - lined with surfactant to decrease surface tension.

  • become thinner as they expand
  • collapse (atelectasis) if surfactant is decreased or alveoli are not inflated
• Lungs:

  • Right lung has three lobes; left lung has two lobes
  • Visceral pleura: tightly attached to the lung surface
  • Parietal pleura: lines the wall of the thorax - attached to the interior of mediastinum