The lungs are a pair of large, spongy organs of the respiratory system in humans and other animals. The human lungs are divided into two parts (left lung and right lung) which are located near the backbone on either side of the heart. The left lung has two lobes while the right lung has three lobes and gets slightly larger. Each lobe further subdivides into hundreds of lobules and each lobule has a thin wall, clusters of alveoli and a bronchiole along with affiliated branches. The main function of the lungs is to perform respiratory activities, which conducts gas exchange during the process of breathing. Water, alcohol and pharmacologic agents can be absorbed and excreted in this process. In addition, the lung is also involved in the synthesis, storage, transformation, and degradation of many substances. As the property of contacting with atmosphere from outside, the lungs are prone to infections or get damaged. Lung diseases become more and more common in present days. A variety of target molecules on lung are used in the detections of related diseases.