What is a main characteristic of emphysema?

Emphysema is primarily characterized by the abnormal enlargement of the air sacs in the lungs, known as alveoli. This enlargement occurs due to the destruction of the elastic fibers in the lung tissue, which impairs the lungs' ability to expel air, leading to reduced surface area for gas exchange. The enlargement makes it difficult for the alveoli to properly function, resulting in decreased oxygen supply to the bloodstream and difficulty in breathing.

Other characteristics, such as inflammation of lung tissues, excess mucus production, and shortness of breath, may be associated with different respiratory conditions or stages of chronic obstructive pulmonary disease but do not specifically define the main characteristic of emphysema. Thus, the focus on the abnormal enlargement of gas-exchange airways directly aligns with the pivotal issue at the core of emphysema.