Class 11 Biology Breathing and Exchange of Gases Respiratory organs

Respiratory organs

  • Lower invertebrates like sponges, exchange O2 with CO2 by simple diffusion over their entire body surface.
  • Earthworms use their moist cuticle and insects have a network of tubes (tracheal tubes) to transport atmospheric air within the body.
  • Special vascularised structures called gills are used by most of the aquatic arthropods and molluscs.
  • Vascularised bags called lungs are used by the terrestrial forms for the exchange of gases.
  • Amphibians, like frogs, can respire through their moist skin also.
  • Mammals have a well-developed respiratory system.


Fig. Lungs


Fig. Gills

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