What is meant by the exchange of gas?

Exchange of gas, or also known as gas exchange, takes place in a lot of different parts of your body. Gas exchange is also known as respiration, and it takes place at a respiratory surface - a boundary between the external environment and the interior of your body. One example of gas exchange is in humans and animals. Gas exchange mostly involves your lungs and your heart. Every time you breathe, gas exchage is taking place. ~ Hexedgirl92 There are surfaces within the respiratory system known as the alveoli. These are paper thin walled, and have the ability to be able to exchange gases quickly from C02 to O2. Then the deoxygenated waste is sent outside of the body, and the o2 is circulated through the body.