Lungs

lung The respiratory organ of air-breathing vertebrates. A pair of lungs is situated in the thorax, within the ribcage. Each consists essentially of a thin moist membrane that is folded to increase its surface area. Exchange of oxygen and carbon dioxide takes place between blood capillaries on one side of the membrane and air on the other. The lung is supplied with air through a bronchus. The lungs are covered by a thin tissue layer called the pleura. The same kind of thin tissue lines the inside of the chest cavity -- also called pleura. A thin layer of fluid acts as a lubricant allowing the lungs to slip smoothly as they expand and contract with each breath.

Bronchiectasis

Bronchiectasis is a term that describes damage to the walls of the large airways, or bronchial tubes, of the lung. Inflammation due to infection or other causes destroys the smooth muscles that allow the bronchial tubes to be elastic and prevents secretions that are normally made by lung tissue to be cleared.
Normal branching of the airways of the lung demonstrates a gentle taper that occurs at each branch point, like the branches of a tree. This tapering results in decreased resistance in the larger branches, enabling mucus or other objects to be funneled to the larger airways and eventually, with a cough, ejected out through the mouth.