Hot Topic :
CYSTIC FIBROSIS
By:  Dr. Barb Goodman
    Cystic fibrosis is an inherited disease that is relatively common in the U.S.  Cystic fibrosis affects multiple parts of the body including the pancreas, the sweat glands, and the lungs.  When someone has cystic fibrosis, they often have lots of lung problems.  The cause of their lung problems is directly related to basic problems with diffusion and osmosis in the large airways of the lungs.
    People without cystic fibrosis have a small layer of salt water in the large airways of their lungs.  This layer of salt water is under the mucus layer which lines the airways.  The mucus layer in the airways helps to clear dust and other inhaled particles from the lungs.
           In people without cystic fibrosis, working cystic fibrosis proteins allow salt (chloride) to enter the air space and water follows by osmosis.  The mucus layer is dilute and not very sticky.
        In people with cystic fibrosis, non-working cystic fibrosis proteins mean no salt (chloride) enters the air space and water doesn't either.  The mucus layer is concentrated and very sticky.
    People with cystic fibrosis have lung problems because: 

    ~Proteins for diffusion of salt into the airways don't
            work.  (less diffusion)
    ~Less salt in the airways means less water in the
            airways.  (less osmosis)
    ~ Less water in the airways means mucus layer is very
            sticky (viscous).
    ~Sticky mucus cannot be easily moved to clear particles from the
            lungs.
    ~Sticky mucus traps bacteria and causes more lung
            infections.
DEFINITIONS ~ LINKS ~ PAGE DIRECTORY
HOT TOPIC ~ EMAIL ~ GUEST BOOK ~ QUIZ 
Meet the makers of this page
This page was created by Patrick Ireland.
It was last updated January 3, 2000.

The American Physiological Society, Education Office
9650 Rockville Pike, Bethesda, MD   20814-3991
Phone: 301-634-7132 -  Fax: 301-634-7098  - Email: education@the-aps.org