Final answer:
Pneumothorax occurs when air enters the chest cavity, causing lung collapse; it can be related to connective tissue abnormalities. Without surgical repair, negative pressure may be restored via external suction. The lungs' alveoli and surface tension play crucial roles in breathing, including for patients with respiratory support.
Step-by-step explanation:
A pneumothorax is a medical condition where air enters the chest cavity, causing a collapsed lung. This can occur spontaneously, and it is believed to be related to subtle abnormalities in connective tissue. Normally, the lungs are attached to the chest wall by liquid adhesion, with a negative gauge pressure that varies with breathing. When air disrupts this attachment, it can result in one or both lungs collapsing. In cases where surgical repair is not undertaken, negative pressure in the chest cavity can be reestablished through non-surgical means like the application of external suction.
Our lungs are comprised of hundreds of millions of alveoli, mucus-lined sacs about 0.1 mm in diameter. Exhalation can occur without muscles, due to the surface tension in these sacs. For individuals on a positive pressure respirator, air is forced into the lungs, but they can exhale naturally. Surface tension facilitates the expulsion of air from the lungs even in paralysis. Additionally, a deep breath is occasionally needed to fully reinflate the alveoli, which is automatically programmed in respirators for medical patients.
The design of the human respiratory system, including the role of surface tension and the pleurae's resistance to damage during normal breathing, emphasizes how our body's structure is optimized for respiration under various conditions, including those requiring medical intervention.