Final answer:
The single fissure in the left lung is the oblique fissure, which separates the superior and inferior lobes. The lung's segmented construction facilitates efficient functioning and the possibility of segment-specific surgical interventions.
Step-by-step explanation:
The left lung is made up of two lobes: the superior (or upper) lobe and the inferior (or lower) lobe. These lobes are separated by a single fissure known as the oblique fissure. The oblique fissure runs diagonally across the lung, separating the two lobes. The left lung is smaller than the right lung to accommodate the heart, which is located just to the left of the center of the chest within the thoracic cavity. In addition to separating the lobes, lung fissures are significant in that they extend deep into the organ and are lined by the visceral pleura, which is part of the thin serous membrane that also wraps around the lungs.
Each lobe of the lung contains bronchopulmonary segments, which are further divided into lobules that receive air from tertiary bronchi. This segmented structure is important for both the efficient functioning of the lungs and the possibility of surgical removal of diseased segments with minimal impact on adjacent structures. The oblique fissure allows these separate segments to function effectively, receiving air and blood from their respective bronchi and arteries.