How Our Lungs Work
The lungs take in oxygen, which cells need to live and carry out their normal functions. The lungs also get rid of carbon dioxide, a waste product of the body's cells.
The lungs are a pair of cone-shaped organs made up of spongy, pinkish-gray tissue. They take up most of the space in the chest, or the thorax (the part of the body between the base of the neck and diaphragm). They are unique in that they are constantly exposed to our external environment – a direct interface with the world outside with every breath we take.
The lungs, with their tiny air sacs called alveoli, are more complex than many other organs. The lungs must play multiple roles – supplier of oxygen, remover of wastes and toxins, defender against hostile intruders. They contain at least three dozen distinct types of cells, each with special tasks and abilities. Some scavenge foreign matter. Others, equipped with delicate, hair-like cilia, sweep the mucous membranes lining the smallest air passages. Still others act on substances crucial to blood pressure control, or serve as sentries to spot invading agents of infection.