Breathing is the process of inhaling or breathing in the air into the lungs and exhaling or breathing out the air from lungs. The process of inhaling and exhaling air is termed as Respiration. All living organisms, from a single bacterial cell to a blue whale, undergo respiration and it is the most important life process as it helps in the production of energy for the different metabolic activities. The movement of air during the process of respiration facilitate gaseous exchange within the environment.
In humans, the gaseous exchange or exchange of gases occurs in the Alveoli, hence it is called the primary sites for the exchange of gases. Here the gaseous exchange of oxygen and carbon dioxide occurs by the simple diffusion process. The exchange of gases also occurs between blood cells and the tissues.
Check here for the free CBSE Class 11 Biology revision notes for the Chapter 17-Breathing and Exchange of Gases.
For more information about the Breathing and Exchange of Gases, click on the below-mentioned links.