Changes

The airways branch out like an upside-down tree, and at the end of each branch are many small, balloon-like air sacs called alveoli (al-VEE-uhl-EYE). In healthy people, each airway is clear and open. The air sacs are small and dainty, and both the airways and air sacs are elastic and springy. When you breathe in, each air sac fills up with air like a small balloon; when you breathe out, the balloon deflates and the air goes out. (See the How the Lungs Work section for details.) In COPD, the airways and air sacs lose their shape and become floppy. Less air gets in and less air goes out because:

The airways branch out like an upside-down tree, and at the end of each branch are many small, balloon-like air sacs called alveoli (al-VEE-uhl-EYE). In healthy people, each airway is clear and open. The air sacs are small and dainty, and both the airways and air sacs are elastic and springy. When you breathe in, each air sac fills up with air like a small balloon; when you breathe out, the balloon deflates and the air goes out. (See the How the Lungs Work section for details.) In COPD, the airways and air sacs lose their shape and become floppy. Less air gets in and less air goes out because:

    * The airways and air sacs lose their elasticity (like an old rubber band).

* The airways and air sacs lose their elasticity (like an old rubber band).

    * The walls between many of the air sacs are destroyed.

* The walls between many of the air sacs are destroyed.

    * The walls of the airways become thick and inflamed (swollen).

* The walls of the airways become thick and inflamed (swollen).

    * Cells in the airways make more mucus (sputum) than usual, which tends to clog the airways.

* Cells in the airways make more mucus (sputum) than usual, which tends to clog the airways.

== COPD ==

== COPD ==

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