Definition

Emphysema is a chronic respiratory disease where
there is over-inflation of the air sacs (alveoli) in the
lungs, causing a decrease in lung function, and often,
breathlessness.

Description

Emphysema is the most common cause of death
from respiratory disease in the United States, and is the
fourth most common cause of death overall. There are
1.8 million Americans with the disease, which ranks fifteenth
among chronic conditions that cause limitations of
activity. The disease is usually caused by smoking, but a
small number of cases are caused by an inherited defect.
Normally functioning lungs are elastic, efficiently
expanding and recoiling as air passes freely through the
bronchus to the alveoli, where oxygen is moved into the
blood and carbon dioxide is filtered out. When a person
inhales cigarette smoke or certain other irritants, his or
her immune system responds by releasing substances
that are meant to defend the lungs against the smoke.
These substances can also attack the cells of the lungs,
but the body normally inhibits such action with the
release of other substances. In smokers and those with
the inherited defect, however, no such prevention occurs
and the lung tissue is damaged in such a way that it loses
its elasticity. The small passageways (bronchioles) leading
to the alveoli collapse, trapping air within the alveoli.

The alveoli, unable to recoil efficiently and move the air
out, over expand and rupture. As the disease progresses,
coughing and shortness of breath occur. In the later
stages, the lungs cannot supply enough oxygen to the
blood. Emphysema often occurs with other respiratory
diseases, particularly chronic bronchitis. These two diseases
are often referred to as one disorder called chronic
obstructive pulmonary disease (COPD).

Emphysema is most common among people aged 50
and older. Those with inherited emphysema may experience
the onset as early as their thirties or fourties Men are more
likely than women to develop emphysema, but female cases
are increasing as the number of female smokers rises.

Causes and symptoms

Heavy cigarette smoking causes about 80