The lungs function to allow the exchange of oxygen and carbon dioxide between the environment and our bloodstream. Each lung is divided into lobes. The right lung has 3 lobes (upper, middle, and lower) while the left lung has only 2 (upper and lower). Each lobe functions as a relatively independent unit, and has its own bronchus to supply air, artery and vein to supply and remove blood, and lymph nodes. Disorders affecting the lungs include tumors, infections, and abnormalities of the vessels or air sacs. Function of the lungs can also be impaired by disorders of the pleural cavity, or space around the lungs.