Overview

Alveoli are microscopic air sacs where oxygen and carbon dioxide exchange occurs across thin alveolar capillary membranes. Surfactant reduces surface tension and prevents alveolar collapse while capillary perfusion enables gas transport. Alveolar integrity is essential for efficient respiration.

Alveolar Structure

Type I pneumocytes provide a thin barrier for gas diffusion while type II pneumocytes produce surfactant and contribute to repair. Alveolar macrophages clear debris and pathogens to maintain sterility. Interstitial tissue supports capillaries and gas exchange.

Gas Exchange Dynamics

Diffusion across the alveolar capillary membrane depends on surface area thickness and partial pressure gradients. Ventilation perfusion matching optimizes oxygen uptake and carbon dioxide removal. Disruption by edema inflammation or fibrosis impairs gas exchange.

Clinical Relevance

Alveolar disease includes pneumonia pulmonary edema and acute respiratory distress syndrome. Imaging with chest radiography and CT identifies consolidation interstitial changes and edema. Supportive care and targeted therapy address underlying causes.