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Emphysema makes it very hard for you to breathe. It causes other kinds of problems, too, because it affects the air sacs in your lungs.

There are more than 300 million tiny air sacs in each lung.¹ They are known as alveoli. They're stretchy, like tiny balloons. They get bigger when you breathe in air and then get smaller when you breathe out. The tubes that carry air to the sacs are rubbery and stretchy, too.

If you have emphysema:

• The walls of some of the sacs start to fall apart
• When this happens, the airways (tubes) can no longer stay open very well
• The remaining air sacs fill up with air, but they can't empty out
• Air gets trapped in your lungs instead of passing into your blood the way it's supposed to.

After a while, the remaining air sacs start to grow together. Then, what started as a lot of small air sacs turns into one big air sac. This makes it harder for your blood to pick up enough oxygen when it flows through your lungs.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.