Animal Respiration

Respiration is the exchange of life-sustaining gases, such as oxygen, between an animal and its environment. Gas exchange occurs by diffusion, moving necessary gases like oxygen into animals and taking away waste gases like carbon dioxide. Although animals have different ways of moving gases in and out of their bodies, gas exchange between the animal and its environment occurs across a moist surface.

Most animal respiration involves four steps:

1. 1-Taking air in (inspiration) and pushing air out (expiration). The term breathing refers to the processes of inspiration and expiration in humans and many other animals.
2. 2-Circulating gases throughout the body.
3. 3-Exchanging needed gases for unnecessary gases
4. 4-Using the needed gases.
5. Depending on the complexity of their bodies and the environment in which they live, animals evolved different systems to achieve respiration. Four basic types of gas-exchange systems occur in animals:
   • Integumentary exchange occurs through the outer surface of some small animals that constantly stay moist.
   • Gills are structures that extend outward from an animal’s body to exchange gases in watery environments.
   • Tracheal exchange systems rely on a network of tubes that end in holes to move oxygen and carbon dioxide throughout the bodies of certain types of insects.
   • Lungs are structures that extend into an animal’s body, creating moist internal surfaces that use diffusion to transport gases into and out of the body.
     source:https://www.dummies.com/education/science/biology/animal-respiration/