And that eventually travels out of our system and to the outside environment. And we'll discuss the structure and the function of the alveolis in much more detail in the next several electrodes. So, as I mentioned earlier, our lungs are based inside the thoracic cavity. So thorax is simply the term that refers to our chest portion of the body. Now, at the bottom of the lungs, we have this sheet of skeletal muscle we call our diaphragm. And the diaphragm not only separates the lungs from the stomach and our small intestine, large intestine, but it also actually moves up and down and that ultimately allows the process of breathing to actually take place.