Introduction to COPD

The Lungs

The lungs are two spongy organs surrounded by a thin, moist membrane called the pleura. Each lung is composed of smooth, shiny lobes; the right lung has three lobes, and the left has two. About 90% of the lung is filled with air; only 10% is solid tissue.

When a person inhales, air travels through the following pathways into the lungs:

• Air is carried from the trachea (the windpipe) into the lung through flexible airways called bronchi.
• Like the branches of a tree, bronchi divide successively into over a million smaller airways called bronchioles.
• The bronchioles lead to grape-like clusters of microscopic sacs called alveoli.
• In each adult lung there are millions of these tiny alveoli. The thin membrane of the alveoli allows oxygen and carbon dioxide to pass to and from capillaries.
• During deep inhalation, the elastic alveoli unfold and unwind to allow this passage to occur.

Capillaries, the smallest of our blood vessels, carry blood throughout the body. Red blood cells carry oxygen throughout the body, and return carbon dioxide to the lungs; white blood cells are the critical infection fighters in our body.