Lung

Lung, major organs in the respiratory system of mammals, birds, reptiles, and most adult amphibians. These elastic organs pick up oxygen from the air and release carbon dioxide back out. The body requires oxygen to burn food for energy; carbon dioxide is a waste product. In humans, air passes through the pharynx and larynx to the airways, the tubes leading to the lungs. One of these tubes, the bronchi, branches off within the lungs, leading to the many alveolar sacs that make up the respiratory units. The exchange of gases takes place within the pulmonary capillaries of this part of the lungs. Lungs help clean the blood of impurities. By exhaling air that makes vocal chords vibrate, they help to effect the sound of speech.

See also: Human body; Respiration.