VPB 121: Veterinary Physiology - II (2+1)

ALVEOLUS

• The pulmonary alveoli are the principal sites of gas diffusion between the air and blood.
• The separation of air and blood, and thus the diffusion distance, is minimal at the alveolar level.

• The alveolar epithelium and the capillary endothelium are intimately associated. Different cells are seen, such as,
  • Type I alveolar cells, predominant,which are simple squamous epithelium and the main site of gas exchange.
  • Type II alveolar (or septal) cells, cuboidal epithelial cells containing microvilli that secrete alveolar fluid containing surfactant. 
  • Alveolar macrophages remove debris from the lungs.
  • Fibroblasts produce elastic fibres.