How does pneumonia primarily affect gas exchange in the lungs?

• A. By increasing the amount of oxygen absorbed
• B. By filling alveoli with fluid or pus
• C. By enhancing the efficiency of alveoli
• D. By dilating the bronchioles

Answer: (B)

Pneumonia primarily affects gas exchange in the lungs by filling the alveoli with fluid or pus. In a healthy lung, alveoli are air-filled sacs where oxygen and carbon dioxide exchange occurs efficiently. When pneumonia occurs, the infection leads to inflammation and the accumulation of fluid, pus, and other exudates within these alveoli. This disrupts the normal air space, impeding the effective transfer of gases.

As a result, the exchange of oxygen into the bloodstream decreases and the removal of carbon dioxide is hindered. The presence of fluid or pus in the alveoli creates a barrier that prevents efficient diffusion of gases, significantly impairing respiratory function. This is why pneumonia can lead to symptoms such as difficulty breathing, reduced oxygen saturation levels, and general respiratory distress.

Enhancing the efficiency of the alveoli or dilating the bronchioles does not occur in pneumonia; instead, the opposite happens. Hence, the filling of alveoli with fluid or pus plays a central role in the alteration of gas exchange due to pneumonia.