Respiration in Organisms Notes

• The need to take in oxygen and expel carbon dioxide is almost universal among organisms.
• The movement of these gases between an organism and its environment, called gas exchange, is accomplished in a variety of ways by different organisms.
• In unicellular aquatic organisms, such as protozoans, and in seaweeds, sponges, jellyfish, and other aquatic organisms that are only a few cell layers thick, oxygen and carbon dioxide diffuse directly between the water and cells.
• In higher animals, there are special organs that help in breathing and respiration.

Animals breathe in many ways:

• Humans, like other land animals with backbones, breathe in oxygen-rich air and breathe out carbon dioxide-rich air with the help of lungs. Lungs are present inside our chest (also called the thorax).

Human respiratory system