1. BREATHING

2. Features of gas exchangesurfaces in animals Thin:toallow gases todiffuseacrossthemquickly. Closetoanefficienttransportsystem: totake gases to and fromtheexchangesurface. Moist: tostop thecellsdying. Largesurfacearea: so that a lot of gas can diffuseacross at thesame time. Wellventilated: a goodsupply of oxygenoftenbroughtbybreathingmovements.

3. RESPIRATORY SYSTEM

4. Ciliated and gobletcells Gobletcells: produces mucus and releasesitontothesurface of thecells. Cilia: They can beat in a coordinatedwaytocarry mucus (withtrapped bacteria and dust) awayfromtheungssurfaces.

5. BREATHING

6. GAS EXCHANGE