lung

lung One of a pair of three-lobed breathing organs located within the right and left sides of the chest. The lungs remove carbon dioxide from the blood and bring oxygen into the blood. Air comes into the lungs via the trachea, traveling evenly into the left and right lungs by means of the left and right bronchi. Each bronchus branches off into several smaller bronchioles, which end in many alveolar sacs. In the tiny alveoli within these sacs, oxygen is exchanged for carbon dioxide in blood delivered back to the heart by the pulmonary veins. Lung function is controlled by several muscles, including the diaphragm muscle beneath the lungs and the intercostal muscles that surround the lungs.