On left lung the oblique fissure divides upper and lower lobes of lung. So, there are 5 lobes. Inner layer is pulmonary pleura. It adheres firmly to the lung. Pleural cavity is the potential, not actual space between the membrane.
Serous fluid is secreted by the cells of the serous membrane and provides an antifriction lubricant.
Pnuemothorax is the puncture of the lungs pleural lining resulting in its collapse. Atelectasis is collapse of lung or part of it. They have walls made up a series of incomplete rings of cartilage, fibrous tissue, muscular fibers and an internal lining of mucous membrane. Right bronchus is larger in diameter and straighter. Left bronchus is about twice as long.