Basic purpose of this lecture is to present on Lung Disease. Here briefly present three main types of lung disease. Airway diseases: These diseases affect the tubes that carry oxygen and other gases into and out of the lungs. These diseases cause a narrowing or blockage of the airways. They include asthma, emphysema, and chronic bronchitis. Lung tissue diseases: These diseases affect the structure of the lung tissue. Scarring or inflammation of the tissue makes the lungs unable to expand fully. Pulmonary circulation diseases: These diseases affect the blood vessels in the lungs. They are caused by clotting, scarring, or inflammation of the blood vessels.