The respiratory membrane through which exchange of oxygen and carbon dioxide takes place consists of

The respiratory membrane is made up of three major layers

1. the thin simple squamous epithelium of alveoli
2. the basement substance (composed of a thin basement membrane supporting the squamous epithelium and the basement membrane surrounding the single layer endothelial cells of capillaries)
3. the endothelium of alveolar capillaries (simple squamous).