The First Line of Defense

• Skin

             - Acid Mantle: Inhibits bacterial growth
             - Keratin: provides resistance against acids, alkalis, and bacterial enzymes

• Mucous Membrane

            - Mucus: traps microoranganisms in respiratory and digestive tracts
            - Nasal Membrane: Filter and trap microorganisms in nasal passages

• Secretions of skin and mucous membrane

             - Lacrimal secrections: an enzyme that destorys microorganisms