Permeability of membrane 2. Surface area 3. Respiratory Organs A. Lungs 1. This, fragile surface area for exchange is protected inside the body. Also has mucus to trap other stuff.
Cilia propel mucus out of lungs and respiratory tract.
Macrophages phagocytose pollution, bacteria, and viruses. Air breathing is energetically less costly than water breathing. As R increases, P decreases. Surfactant lowers wall tension in small alvioli and raises it in larger alveoli. Site of loss of heat and water.