Breathe in as deeply as you can. Watch your chest rise as your lungs fill with air, then fall as you exhale. Now, hold your breath for just a few seconds. Do you feel how much you want to take a gulp of air? That's because the oxygen in the air is vital to life, and it is the job of your lungs and respiratory system to provide oxygen for all the cells in the body. Just as important is the job they do of getting rid of carbon dioxide, a waste gas of the body that you exhale with every breath. This system also makes it possible for you to talk and sing. Let's take a look at how this process works.