Emphysema is a disease affecting the lungs. People with emphysema are often short of breath and find exercise difficult. Explain what happens to the lungs in this disease to cause the symptoms mentioned.

Emphysema affects the structure of the lungs called the alveoli. Each healthy alveolus has a large surface area in order for maximum diffusion of oxygen in the lungs.

If someone is affected by emphysema, the alevoli are damaged and become flattened. This decreases the surface area, and therefore, the amount of oxygen that can diffuse into the blood (gas exchange is impaired). Mucus and fluid can also fill the alveoli which reduces efficient gass exchange further. The reduced oxygen levels in the blood affect respiration in the individual so that there is less oxygen and make it hard to breath. This is most evident in exercise when the demand for oxygen is higher. The muscles receive less oxygen supply from the blood and cannot produce enough energy (ATP).