What characteristic allows the lungs to function as separate airtight sacs?

• A. Pleural linkage
• B. Elastic tissue
• C. Pleural pressure
• D. Negative interpleural pressure

Answer: (A)

The characteristic that allows the lungs to function as separate airtight sacs is pleural linkage. This concept refers to the connection between the lungs and the thoracic wall through the pleural membranes, which create a sealed, fluid-filled compartment around each lung. This pleural linkage ensures that each lung is individually pressurized and can expand and contract independently of one another, while still being influenced by changes in thoracic cavity pressure during breathing.

The pleural membranes create surface tension due to the pleural fluid, which effectively "links" the lungs to the chest wall. This linkage is essential for effective lung inflation, as it maintains adherence and prevents the lungs from collapsing completely. Additionally, this separation allows for potential differences in pressure and volume between the two lungs, which can occur during situations like disease or trauma, where one lung may be compromised while the other continues to function normally.

Other options, while relevant to lung function, do not specifically relate to the characteristic of airtight separation between the lungs. For instance, elastic tissue refers to the recoil ability of the lung tissue itself, pleural pressure is the pressure within the pleural cavity that influences lung inflation, and negative interpleural pressure contributes to lung expansion but does not strictly define the separation of the lungs as