ALVEOLI AND RESPIRATORY MEMBRANE

• Alveoli - small, air-filled chambers where the air and the blood come into close contact with each other
• 2 types of cells that form the alveolar wall:

  • Type I pneumocytes - gas exchange between alveolar air and the blood takes place through these cells; thin squamous epithelial cells that form 90% of the alveolar surface
  • Type II pneumocytes - round or cube-shaped secretory cells that produce surfactant, which makes it easier for the alveoli to expand during inspiration
• Respiratory Membrane - where O2 enters the blood and CO2 exits the blood
• Layers of the Respiratory Membrane (superficial to deep):

  • Alveolar fluid
  • Alveolar epithelium
  • Basement membrane of alveolar epithelium
  • Interstitial space
  • Basement membrane of capillary endothelium
  • Pulmonary capillary endothelium