What characterizes emphysema?

Emphysema is characterized by the destruction of lung parenchyma, which refers to the functional lung tissue. In emphysema, the alveoli—the tiny air sacs in the lungs—become damaged and lose their elasticity, leading to difficulty in expiration. This destruction primarily results in larger air spaces instead of the normal small alveoli, reducing the surface area available for gas exchange and contributing to the hallmark symptoms of the condition, such as dyspnea (shortness of breath) and reduced exercise tolerance.

While increased lung volume may occur as a result of the air trapping associated with emphysema, it is not the defining characteristic of the disease; rather, it is a consequence. Unlike constriction of the airways or inflammation, which are more characteristic of other respiratory conditions like asthma or chronic bronchitis, the key feature of emphysema is this irreversible damage and destruction of the lung tissue.