By Simran Jayasinghe
The respiratory system controls your breathing. When you inhale, your diaphragm moves down, letting your lungs expand and take in more air. Air comes in through you mouth, into your trachea, and into your lungs. Your trachea branches out into bronchi, and the bronchi end in small air sacs called alveoli. Each alveoli is wrapped in tiny blood vessels. The air goes to the alveoli, and the oxygen in the air moves through the thin membrane of the alveoli, and into the blood vessels, and the blood carries it to our cells. Carbon dioxide, a waste product made in your cells, gets carried by the blood and is taken to the alveoli. In the alveoli, the carbon dioxide moves from the blood to the air that we exhale. The exhaled air goes up your trachea, and out of your mouth. As you exhale, your diaphragm moves up, forcing the air out.
