Respiration process in animals

Respiration is an oxidation process which involves degradation of a complex organic compound, hence carbon dioxide and water and energy are produced. Respiration process can be divided into two phases –

External Respiration or Breathing

In this process, animals intake oxygen and release carbon dioxide. It is also known as breathing. This is mainly two phases.

• Inspiration: It is the process by means of which oxygen is taken to the lungs.
• Expiration: During expiration, carbon dioxide is expelled out from the respiratory organs into the environment.

The process of exchange gases varies in different animals.

1. Through Plasma Membrane

In unicellular animals, such as amoeba, exchange of gases takes place through cell surface. They absorb oxygen from the surrounding air or water and give out carbon dioxide through plasma membrane by diffusion.

2. Through Body Wall or Skin

Tapeworms, earthworms, and leeches use their skin for the exchange of gases. The skin of Earthworms is very thin and moistened. Many blood cells are spread on this skin. These blood cells are known as capillaries. The exchange of gases occurs at capillaries. They die of suffocation if their skin is dried up.

 

Amphibians such as frogs use more than one organ of respiration during their life. They breathe through gills while they are tadpoles. Mature frogs breathe mainly with lungs and also exchange gas with the environment through skin.

3. Through Tracheal System

In insects like cockroaches, grasshopper, transportation of gas or gaseous exchange take place by a special type of fine tubes is called tracheae.

Air containing oxygen enters through spiracles into the tracheal tubes. It then diffuses into the body tissue and reaches every cell in the body. Carbon dioxide released from the cells goes into the tracheal tubes and comes out through spiracles.

4. Through Gills

A majority of aquatic animals like fish and prawns breathe through special organs called gills. Gilla are projections of the skin that help in using oxygen dissolved in water. Gills contain blood vessels which help in exchange of gases.

Fish live in water. To get oxygen dissolved in water, fish gulp water through the mouth and pump it over the gills. Water passes into the gill chamber through gill slits. In each chamber, the water passes over the filaments. They absorb oxygen from the water and replace it with carbon dioxide formed. The water then passes out through the gill opening and this process is repeated again and again.

5. Through lungs

Amphibians, mammals, and birds exchange gases through special respiratory organs called lungs. Lungs are air-filled sac-like structures in the chest cavity. They are connected to the outside by a series of tubes and small opening.