NCERT Solutions For Class 11 Biology Chapter 17: Breathing and Exchange of Gases

O₂ has to be continuously provided to the cells and CO₂ produced by the cells has to be released. This process of exchange of O₂ from the atmosphere with CO₂ produced by the cells is called breathing, commonly known as respiration. Breathing involves two stages: inspiration during which atmospheric air is drawn in and expiration by which the alveolar air is released out. The movement of air into and out of the lungs is carried out by creating a pressure gradient between the lungs and the atmosphere. The exchange of gases also occurs between blood and tissues. O₂ and CO₂ are exchanged in these sites by simple diffusion mainly based on pressure/concentration gradient.

• Respiratory Organs in Animals 

Respiratory organs in animals are a system of organs responsible for inhaling oxygen and exhaling carbon dioxide in humans. The mode of external respiration varies greatly from an organism to organism. The important respiratory organs in living beings include- the lungs, gills, trachea, and skin.

• Respiratory System in Humans

The respiratory tract in human beings is made up of nostrils, nasal chamber, larynx, pharynx, epiglottis, trachea, bronchioles, bronchi, alveoli, and lungs.

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