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Tracheobronchial Tree
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Tracheobronchial Tree

The tracheobronchial tree comprises the distal portion of the lower respiratory tract.
Tracheobronchial Tree
The tracheobronchial tree comprises the distal portion of the lower respiratory tract.
Review respiratory system
Photos
Key structures:
Trachea:
  • Cartilaginous "trunk" of the tree.
  • Comprises 15 – 20 C-shaped cartilaginous rings, are stacked vertically and connected via anular rings.
  • Trachealis posterior forms posterior wall of trachea; moves to accommodate foods passing posteriorly through the esophagus.
Bronchi:
  • Primary bronchi enter the lungs.
  • Secondary bronchi serve lobes of lung ("lobar" bronchi).
  • Tertiary bronchi serve bronchopulmonary segments ("segmental" bronchi); 10 on the right, 8-10 on the left.
Bronchioles:
  • Numerous, and narrow as they branch.
  • Have more smooth muscles in their walls, but still have cartilage in their walls.
  • Terminal bronchiole is the final passageway of the conduction portion of the respiratory system.
Respiratory bronchioles:
  • Demarcate the respiratory portion of the respiratory tract.
  • Thin walls allow some gas exchange.
Alveolar ducts:
  • Arise from respiratory bronchioles.
Alveolar sacs:
  • Terminal ends of the alveolar ducts.
Alveoli:
  • Thin-walled out-pockets of the alveolar sacs.
  • Surrounded by pulmonary capillaries.
  • Facilitate gas exchange between the respiratory and cardiovascular systems.
Lungs:
  • Hundreds of millions of alveoli.
  • Left lung = superior and inferior lobes; heart nestles into medial left lobe.
  • Right lung = superior, middle, and inferior lobes.
Review
Clinical Correlations:

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