Final answer:
The pleurae do not contract during inhalation; their primary functions are to produce pleural fluid and create cavities. It is the contraction of the diaphragm and intercostal muscles that are responsible for creating the pressure changes that allow the lungs to expand and fill with air during inhalation.
Step-by-step explanation:
The pleurae are crucial in respiratory mechanics, but they do not contract during inhalation, which is the function that is not represented in the list provided. Instead, the pleurae serve to produce pleural fluid and create cavities, which play a key role in breathing.
The pleural fluid secreted by mesothelial cells acts as a lubricant between the pleural layers, reduces friction during breathing, and maintains lung position by creating surface tension. This allows the lungs to follow the chest wall's motion during respiration. However, during inhalation, it is the diaphragm and intercostal muscles that create the negative pressure necessary for the lungs to expand and fill with air, not the pleurae themselves. As the diaphragm contracts and flattens, the thoracic cavity enlarges, and the intercostal muscles expand the chest. Consequently, the pressure drops within the pleural cavities and lungs, allowing air to flow inward. During exhalation, these muscles relax, the chest recoils, and air is expelled passively due to elastic forces within the lungs and the return of the diaphragm to its domed shape.