health

Emphysema is a lung disease in which a person’s ability to breathe easily
and deeply is steadily weakened over time by the destruction of lung
tissue. The human lung consists of tissue containing millions of tiny air
sacs called alveoli, which are arranged like bunches of grapes around very
small air tubes called bronchioles. There are about 300 million alveoli in
each lung. When a person breathes in air, the air travels from the nose
and mouth through the windpipe and then into the right and left
bronchi, which are the main air passages into each of the two lungs. The
bronchi divide and subdivide repeatedly into smaller and smaller air passages,
finally ending in the bronchioles and alveoli.
In a healthy person, oxygen from the air that has been taken in is
exchanged in the walls of the alveoli for carbon dioxide in the person’s
blood. When the person breathes out, the carbon dioxide leaves the body
in the air that travels out from the lungs and through the upper airway to
the nose and mouth.
To perform its function effectively, the tissue in the lungs that separates
the alveoli from one another needs to be as elastic as possible. The
alveoli contain tiny elastic fibers in their cell walls that allow them to act
like miniature balloons. What happens in emphysema is that smoke or
other irritants causes the alveoli to become inflamed and lose their elasticity.
The bronchioles start to collapse, which traps air inside the alveoli
and overstretches them. In time the alveoli rupture, leading to the formation
of fewer but larger air sacs in the lungs. These larger and less flexible
sacs are less efficient in forcing air out of the lungs when the person
breathes out. As a result, the person has to breathe more frequently or
breathe harder in order to get enough oxygen and get rid of carbon
dioxide.
In addition to the loss of elasticity in the alveoli, the cells in the airways
secrete more mucus than usual, which collects in the airways and
clogs them, making breathing even more difficult.