How is the process of respiration performed in organisms?

The process of respiration in organisms is performed through breathing, commonly known as respiration. As you have read earlier, oxygen (O₂) is utilised by the organisms to indirectly break down simple molecules like glucose, amino acids, fatty acids, etc., to derive energy to perform various activities. Carbon dioxide (CO₂) which is harmful is also released during the above catabolic reactions. It is, therefore, evident that O₂ has to be continuously provided to the cells and CO₂ produced by the cells have to be released out. This process of exchange of O₂ from the atmosphere with CO₂ produced by the cells is called breathing, commonly known as respiration. Place your hands on your chest; you can feel the chest moving up and down. You know that it is due to breathing. How do we breathe?