The breathing tubes, or bronchi, leading to the air sacs (alveoli)
are lined with cells that produce
mucus. Normally, the cells produce a thin, runny mucus
that coats the surface of the airways.
Foreign particles, such as dust and germs, constantly enter the
airways and become trapped in the mucus. Tiny hairs called cilia on the surface
of the breathing tubes sweep the mucus and foreign particles upward into the
larger air passages and then up to the throat where they can be swallowed or
Cystic fibrosis causes the mucus that coats the
breathing tubes to become so thick and sticky that the cilia are unable to
sweep the germs and other particles up and out of the lungs. The trapped
bacteria lead to frequent, serious infections and permanent lung damage.
In response to infections, the body's
immune system sends white blood cells to the lungs to
attempt to destroy the infection. White blood cells release chemicals that kill
both bacteria and surrounding normal cells. After attacking the bacteria, the
white blood cells die, adding to the thickness of the mucus and destruction of
In the upper respiratory tract, thick, sticky mucus may also clog
the nasal passages and sinuses. Small growths, or polyps, on the inner lining
of the nose may develop from repeated infection and inflammation.
Complications of cystic fibrosis usually involve some aspect of
long-term impaired respiratory function. These complications may include:
July 18, 2013
John Pope, MD - Pediatrics
& Susanna McColley, MD - Pediatric Pulmonology
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