The respiratory system includes the nose, mouth, throat, vocal cords, lungs, and diaphragm. It introduces oxygen into the body and releases carbon dioxide through a series of steps. Air enters through the nose or mouth and is filtered and humidified before reaching the lungs. It then passes through the pharynx, larynx, trachea, bronchi and bronchioles into tiny air sacs called alveoli where oxygen passes into blood and carbon dioxide leaves blood to be exhaled. The diaphragm and lungs work together to inhale and exhale air which is distributed through the body by the bloodstream.