B5d - The Respiratory System

B5d - The Respiratory System

1. Methods of gaseous exchange restrict them to their habitats

   • Amphibians need moist habitats. Frogs have simple lungs and con obtain oxygen from the floor of their mouths
     • Skin is permeable to gasses they are susceptible to excessive water loss. Some survive in dry areas with a layer a slime
   • Fish Gills Only work in water. They have a single circulatory system. Blood flows from the heart to the gills. Gills have filaments giving a large surface area. Each filamane tis well supplied with blood
     • As they swim it gulps water into its mouth. Then with the closed mouth , it raises the floor of the mouth and forces water out over the gills. Oxygen dissolved in the water diffuses into the fish's blood at the gills. CO2 diffuses from the blood in the gills into the water. Oxygenated blood flows to it's organs

2. Ventilation

   • Breathing in
     • Intercostal muscles contract
       • Rib Cage moves up and out
         • Diaphragm contracts
           • Diaphragm flattens
             • Volume of the thorax increases
               • Pressure decreases
                 • Pressure is lower than atmospheric pressure. therefore air is taken in

3. Alveoli

   • Oxygen diffuses from the alveoli into the bloodstream
   • CO2 that has entered blood at body tissues diffuses from blood into the alveoli to be breathed out
   • Adaptations
     • Permeable
     • Moist Surface
     • Large surface area
     • Good blood supply
     • Thin lining (1 cell think)

4. Spirometer

   • Tidal Volume- The volume of air moving in and out of the lungs during breathing at rest
   • Vital Capacity- Largest possible volume change in the lungs during breathing (max inspiration and max expiration)
   • Residual Volume- Volume remaining in the lungs even after maximum expiration
   • Total Lung Capacity- Vital capacity + Residual Volume

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