How are oxygen and carbon dioxide exchanged in our body during respiration?

When we breath in, the air sacs or alveoli get filled with air containing oxygen. The alveoli are surrounded by thin blood vessels called capillaries carrying blood in them. So, the oxygen of air diffuses out from the alveoli into the blood. Blood carries this oxygen to all the parts of the body. When it passes through the tissues, the oxygen in the blood diffuses into the cells and mixes with the digested food to release energy. Carbon dioxide produced during respiration in the cells diffuses into the blood which is carried to the lungs. Inside the lungs, the carbon dioxide diffuses into the alveoli.


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