The Lungs are paired organs in the chest that perform respiration. Each human has two lungs. Each lung is between 10 and 12 inches long. The two lungs are separated by a structure called the mediastinum. The mediastinum contains the heart, trachea, esophagus, and . The lungs are covered by a protective membrane called the pulmonary pleura.
Lung function normally peaks in the late teens and early twenties. After the early twenties, lung function declines about 1 percent a year over the rest of a person's lifetime. Lung function decreases about 2 percent a year for people who smoke.....read more