Smoker's Lung: Pathology Photo Essay (cont.)
What are the abnormalities (diseases) in smoker's lung?
The major abnormalities in smoker's lung are grouped under the label of
Chronic Obstructive Pulmonary Disease (COPD).
It is estimated that 40 million people worldwide suffer from COPD. COPD is the 4th leading cause of death in the USA. Even more disturbing is the fact that COPD is the only one of the
"top 5" causes of death to increase in the past decade. While COPD has been thought of as a disease of men, it is estimated that by the year 2010 there will be more women than men affected by COPD. These statistics are especially sad because COPD is preventable disease by
stopping smoking;
unfortunately, this is easier said than done. About 70% of smokers want to quit, but only 7% who try are smoke free after one year; however, one should not give up. Numerous tries, sometimes more than 10, and professional help often are needed, but the health benefits of smoking cessation make it worth the effort.
COPD is made up of two major, related diseases. One, emphysema, involves the lung alveoli, and the other, chronic bronchitis, involves the bronchial airway. (Both conditions are discussed below.) In this essay, I will use the term chronic bronchitis to include chronic bronchiolitis and chronic respiratory bronchiolitis. I do this because these three conditions have the same pathology (structural abnormalities), cause the same symptoms, and differ only in their location in the airway. At any rate, some smokers primarily have emphysema and some primarily have chronic bronchitis. Most, however, have a combination of these two diseases.
What happens to the lung in emphysema?
In emphysema, the walls of the air sacs (alveolar septae) are destroyed.
Consequently, the individual air spaces (alveoli) become larger but irregular
and decreased in number. These larger spaces are less efficient than normal
sized alveoli for gas exchange. Thus, emphysema impairs diffusion of oxygen and
carbon dioxide (gas exchange). The more extensive the emphysema, the poorer the
gas exchange becomes. Also, in emphysema, the capillaries are destroyed with the
rest of the alveolar wall. As a result, emphysema also disrupts the normal blood
supply. Figure 4 contrasts the nasty
appearance of a smoker's emphysematous lung with a normal lung.
Figure 4: SMOKER'S AND NON-SMOKER'S LUNGS
(Roll mouse over each image to see which is which.)
Emphysema usually starts in the upper lobes of the lung and, as depicted in
this photo, is more severe in the upper lobes for complex reasons. That is, the
abnormal (enlarged and irregular) air sacs (alveoli) are more prominent in the
upper lobes. (The blood vessels in the lungs should not be mistaken for the
abnormal air sacs.)
In someone with severe emphysema, the entire chest actually can enlarge. What
probably happens is that the patient's extra (compensatory) efforts to suck in
as much air as possible (to increase ventilation) contribute to enlarging the
lungs and the chest. Thus, a person with severe emphysema often develops what
has been described as a barrel-chest.
Next: How does emphysema come about? »
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