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
Effects of cystic fibrosis on lung and respiratory function
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:
Coughing up blood. Coughing up small amounts of
blood is often a symptom of chest infection. Coughing up very large amounts of
blood can be life-threatening. If you are coughing up blood, call your
Pneumothorax, a buildup of air between
the lungs and chest wall that causes the lung to collapse. This affects adults
with cystic fibrosis more often than children.
pressure in the lungs (pulmonary hypertension). The arteries in the lungs
narrow (constrict) in response to impaired oxygen flow between the lungs and
blood cells. The heart must pump harder to move blood through the blood
vessels, which increases pressure in the lungs.
Enlarged, damaged airways (bronchiectasis) which can lead to infection.