Emphysema causes lung damage. You have airways in your lungs called bronchioles, and at the end of those airways are tiny air sacs called alveoli. Alveoli and the cells that support them usually hold your bronchioles open so air can pass through and oxygen can be distributed into your bloodstream. However, when you have emphysema, your alveoli get damaged and your bronchioles may collapse. To put it simply, emphysema causes your airways to collapse and makes it difficult to breathe. The end result is the body not getting enough oxygen.