at the top of ones lungs

lung 

Main Entry: lung
Pronunciation: 'l&[ng]
Function: noun
1 a : one of the usually two compound saccular organs that constitute the basic respiratoryorgan of air-breathing vertebrates, that normally occupy the entire lateral parts of the thorax and consist essentially of an inverted tree of intricately branched bronchioles communicating withthin-walled terminal alveoli swathed in a network of delicate capillaries where the actual gaseous exchange of respiration takes place, and that in humans are somewhat flattened with a broad baseresting against the diaphragm and have the right lung divided into three lobes and the left into two lobes b : any of various respiratory organs of invertebrates
2 : a mechanical device for regularly introducing fresh air into and withdrawing stale air from the lungs : RESPIRATOR —see IRON LUNG —lunged adjective

lung (lŭng)
n.
Either of the two saclike organs of respiration that occupy the pulmonary cavity of the thorax and in which aeration of the blood takes place. It is common for the right lung, which is divided into three lobes, to be slightly larger than the left, which has two lobes.

lung   (lŭng)  Pronunciation Key  Either of two spongy organs in the chest of air-breathing vertebrate animals that serve as the organs of gas exchange. Blood flowing through the lungs picks up oxygen from inhaled air and releases carbon dioxide, which is exhaled. Air enters and leaves the lungs through the bronchial tubes. A similar organ found in some invertebrates.