The meaning and function of respiration.

The cells of most living organisms require oxygen. It is necessary that oxygen constantly enters the cells, and carbon dioxide is removed. Animals have respiratory systems for this. Some organisms are able to breathe over the entire surface of their skin, such as earthworms. Some have lungs. These are mammals, rodents and others. Aquatic inhabitants have gills. Amphibians have both lungs and gills. Without constant gas exchange, the death of the body occurs very quickly. A person dies in 4-7 minutes without air.