Pulmonary fibrosis

Pulmonary fibrosis is what happens when the tissue deep inside the lungs becomes scarred over time. Fibrosis means exactly that: scar. And a scar does not behave like the original tissue. That tissue grows thick and stiff, so breathing takes more effort, and because the lungs are where oxygen passes into the blood, the blood can end up with less oxygen than it needs. Elastic tissue slowly shot through with stiff seams: it is still there, but it no longer stretches the way it did.

There are several known causes, and they do not resemble one another. They include environmental pollutants and some medications, and also some connective tissue diseases; connective tissue is the body's supporting tissue, and it can become inflamed in certain diseases. Interstitial lung disease belongs on the list too; the name covers a large group of diseases that inflame or scar the lung.

But in most cases no cause is found, and then the disease goes by another name: idiopathic pulmonary fibrosis. Idiopathic means of unknown cause. And what that form affects is the tissue surrounding the alveoli, the tiny air sacs where oxygen passes into the blood.