Root of the lung in the context of "Pleural cavity"

A bronchus (/ˈbrɒŋkəs/ BRONG-kəs; pl.: bronchi, /ˈbrɒŋkaɪ/ BRONG-ky) is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi to branch from the trachea at the carina are the right main bronchus and the left main bronchus. These are the widest bronchi, and enter the right lung, and the left lung at each hilum. The main bronchi branch into narrower secondary bronchi or lobar bronchi, and these branch into narrower tertiary bronchi or segmental bronchi. Further divisions of the segmental bronchi are known as 4th order, 5th order, and 6th order segmental bronchi, or grouped together as subsegmental bronchi.The bronchi, when too narrow to be supported by cartilage, are known as bronchioles. No gas exchange takes place in the bronchi.

The pleural cavity, or pleural space (or sometimes intrapleural space), is the potential space between the pleurae of the pleural sac that surrounds each lung. A small amount of serous pleural fluid is maintained in the pleural cavity to enable lubrication between the membranes, and also to create a pressure gradient.

The serous membrane that covers the surface of the lung is the visceral pleura and is separated from the outer membrane, the parietal pleura, by just the film of pleural fluid in the pleural cavity. The visceral pleura follows the fissures of the lung and the root of the lung structures. The parietal pleura is attached to the mediastinum, the upper surface of the diaphragm, and to the inside of the ribcage.

Sarcoidosis, also known as Besnier–Boeck–Schaumann disease, is a non-infectious granulomatous disease involving abnormal collections of inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph nodes. Less commonly affected are the eyes, liver, heart, and brain, though any organ can be affected. The signs and symptoms depend on the organ involved. Often, no symptoms or only mild symptoms are seen. When it affects the lungs, wheezing, coughing, shortness of breath, or chest pain may occur. Some may have Löfgren syndrome, with fever, enlarged hilar lymph nodes, arthritis, and a rash known as erythema nodosum.

The cause of sarcoidosis is unknown. Some believe it may be due to an immune reaction to a trigger such as an infection or chemicals in those who are genetically predisposed. Those with affected family members are at greater risk. Diagnosis is partly based on signs and symptoms, which may be supported by biopsy. Findings that make it likely include large lymph nodes at the root of the lung on both sides, high blood calcium with a normal parathyroid hormone level, or elevated levels of angiotensin-converting enzyme in the blood. The diagnosis should be made only after excluding other possible causes of similar symptoms such as tuberculosis.