The lungs are conical in shape, each having an apex, base, three borders, and two surfaces. Each lung also has a hilum, where the root of the lung enters transmitting various structures. The lungs are divided into lobes: the right lung consists of three lobes, while the left one - of two. Each lobe is subdivided into bronchopulmonary segments based on the segmental bronchi. The segments of the lung are conical in shape, separated from each other by layers of connective tissue. Each bronchopulmonary segment is a discrete anatomical and functional unit, therefore surgical removement of a segment does not affect the function of the other segments.