Respiratory System - Introduction

Description:

The mechanism of breathing varies among different organisms. Breathing habits are highly dependent on the habitat and the levels of organisation of an organism.

The respiratory system varies from simple diffusion in lower invertebrates to more well developed structures in higher animals such as mammals.

Different organisms have different modes of respiration −

• Exchange of gases in case of lower invertebrates like sponges, flatworms etc. happen through simple diffusion.
• Earthworms exchange gases through their moist cuticle.
• Some aquatic organisms have special structures called gills for respiration.
• Terrestrial organisms have lungs for the exchange of gases.
• Fishes use gills while birds and mammals use lungs for respiration.
• Amphibians like frogs can respire through their moist skin along with the respiration through lungs.