Respiratory System in Human Body

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Respiratory System in Human Body

All physical and chemical reactions in which atmospheric air oxidizes food in the body cells resulting in production of energy and liberation of CO₂ are included in respiration.

Types of Respiration

I. Anaerobic Respiration

When nutrients are oxidized without using O₂ (also called fermentation).

In yeast, glucose forms ethyl alcohol and CO₂.

In bacteria and muscles, glucose is converted into lactic acid. Endoparasites like Ascaris, Fasciola, Taenia also respire anaerobically.

It is a low energy yielding process.

II. Aerobic Respiration

Cells utilize O₂ for oxidizing nutrients. O₂ is used either from atmospheric air or from water.

It is found in most plants and animals.

It provides much more energy than the anaerobic one.

It involves:

1. External Respiration: Gaseous exchange of O₂ and CO₂ between blood and air (or water).
2. Transport of gases to the tissues.
3. Internal Respiration: Gaseous exchange between blood and tissues.
4. Cellular Respiration: Oxidation of nutrients in the cells and liberation of energy.