The respiratory distress that accompanies emphysema is caused by:
a) repeated exposure to cigarette smoke.
b) chronic stretching of the alveolar walls.
c) massive constriction of the bronchioles.
d) acute fluid accumulation in the alveoli.
The Correct Answer and Explanation is:
Correct Answer: b) chronic stretching of the alveolar walls.
Explanation:
Emphysema is a type of chronic obstructive pulmonary disease (COPD) characterized primarily by chronic damage and irreversible enlargement of the alveoli (the small air sacs in the lungs where gas exchange occurs). This damage is largely due to the chronic stretching and destruction of alveolar walls, making option b the correct answer.
In a healthy lung, alveoli are elastic structures that expand and recoil during inhalation and exhalation. In emphysema, proteolytic enzymes like elastase—often released in response to chronic irritation (especially from cigarette smoke)—gradually break down the elastic fibers of the alveolar walls. This leads to the loss of surface area for gas exchange and reduced elastic recoil, which makes it extremely difficult for the patient to exhale air efficiently.
As the alveolar walls become damaged and coalesce into larger, less efficient air spaces, air becomes trapped in the lungs, leading to hyperinflation. The lungs become less compliant, and the diaphragm flattens, further impairing the mechanics of breathing. This contributes significantly to respiratory distress, as the body struggles to eliminate carbon dioxide and obtain sufficient oxygen.
Although cigarette smoke (option a) is a major risk factor for emphysema, it is not the direct cause of the respiratory distress—rather, it initiates the process that eventually leads to chronic alveolar wall destruction.
Option c, massive constriction of bronchioles, is more characteristic of asthma, not emphysema.
Option d, acute fluid accumulation in the alveoli, describes pulmonary edema, commonly seen in left-sided heart failure, not emphysema.
In conclusion, the respiratory distress in emphysema is due to chronic stretching and destruction of alveolar walls, leading to air trapping, inefficient gas exchange, and difficulty exhaling, all of which progressively impair respiratory function.