The pleural space is located anatomically between the visceral membrane, which is firmly attached to the lungs, and the parietal membrane which is firmly attached to the chest wall (a.k.a. ribcage and intercostal muscles, muscles between the ribs). The pleural space contains pleural fluid. This fluid holds the two membranes together by surface tension, as much as a drop of water between two sheets of glass prevents them from separating. Because of this, when the intercostal muscles move the ribcage outward, the lungs are pulled out as well, dropping the pressure in the lungs and pulling air into the bronchi, when we 'breathe in'. The pleural space is maintained in a constant state of negative pressure (in comparison to atmospheric pressure). If the chest wall, and thus the pleural space, is punctured, blood, air or both can enter the pleural space. Air and/or blood rushes into the space in order to equalise the pressure with that of the atmosphere. As a result, the fluid is disrupted and the two membranes no longer adhere to each other. When the rib cage moves out, it no longer pulls the lungs with it. Thus the lungs cannot expand, the pressure in the lungs never drops and no air is pulled into the bronchi. Respiration is not possible. The affected lung, which has a great deal of elastic tissue, shrivels in what is referred to as a collapsed lung.
Hemopneumothorax
Hemothorax
Urinothorax
Chylothorax
Hydropneumothorax
Pneumothorax
Pulmonary hematoma
Pneumomediastinum