What condition is characterized by damaged alveoli and shortness of breath?

Emphysema is characterized by the destruction of alveoli, which are the tiny air sacs in the lungs where gas exchange occurs. When these alveoli are damaged, they lose their elasticity and the surface area available for gas exchange is significantly reduced. This leads to difficulty in exhaling air, resulting in shortness of breath, especially during physical activity. People with emphysema often experience a chronic cough and wheezing as well.

Asthma, pneumonia, and bronchitis can also cause respiratory symptoms but involve different underlying mechanisms. Asthma is primarily an inflammatory condition that results in narrowed airways, pneumonia involves infection leading to fluid accumulation in the lungs, and bronchitis is characterized by inflammation of the bronchial tubes. While these conditions can lead to shortness of breath, they do not involve the specific destruction of alveolar tissue that defines emphysema. Thus, the key characteristic of damaged alveoli in emphysema makes it the correct answer.