Oxygen is needed by the body to turn food into energy. As we breathe, our body inhales molecules of oxygen and exhales carbon dioxide, a by-product of the whole process of respiration.
The respiratory system in our body ensures that our body absorbs enough oxygen, and releases enough carbon dioxide, to keep functioning normally, even as we use more energy to exercise or play sports.
The system is composed of special organs and structures to make respiration possible.
Air enters the body through the nose and passes through several airways, including the pharynx (throat), the larynx (voice box) and the trachea (windpipe). As the trachea nears the lungs, it branches into a pair of smaller airways called bronchi.
Each bronchus connects to the lung on its side, and further splits into many smaller bronchioles. At the end of each bronchiole is a tiny sac of air, called an alveolus, which is the functional unit of the lung. In the alveoli, oxygen from inhaled air is transferred to the blood, and carbon dioxide is transferred to the air sac to be exhaled into the atmosphere.
In this human respiratory diagram quiz, you’ll get to brush up on your knowledge of the organs and processes related to respiration, as well as review the mechanism of breathing itself.