What does the respiratory system do?

Your respiratory system is made up of a series of tubes and passages that transport the air you breathe. It allows an exchange of gases between the air, your blood, and your tissues. As you inhale, or breathe in, air enters your body through your mouth and nose. Your lungs are organs that fill with air when you inhale. They expand like a balloon. The they empty air when you exhale or breathe out. This movement is controlled by the contractions of a large, flat sheet of muscle called a diaphragm. Air is drawn down into your lungs into branched tubes. These tubes are surrounded by capillaries. A capillary is a tiny blood vessel.