Now, this respiration process is not the same thing as cellular respiration that takes place within the individual cells of our body. Cellular respiration is when our cell uses oxygen to produce ATP and produces carbon dioxide as a byproduct. But respiration is simply the breathing process, the process by which we inhale oxygen and we exhale. We expel our carbon dioxide. So our lungs are specialized organs that are responsible for carrying out this process of breathing. So inside our lung, inside the lungs, we have many tiny microscopic, specialized saclike structures we call alveoli.