Your lungs make oxygen available to your body and remove other gases, such as
carbon dioxide, from your body. This process takes place 12 to 20 times per
minute.
When you inhale through your nose or mouth, air travels down the pharynx
(back of the throat), passes through your larynx (voice box) and into
your trachea (windpipe). Your trachea is divided into two air passages
called bronchial tubes. One bronchial tube leads to the left lung, the
other to the right lung. For the lungs to perform their best, the airways need
to be open during inhalation and exhalation and need to be free from inflammation
(swelling) and abnormal amounts of mucus.
The right lung has three sections called lobes and is a little larger
than the left lung, which has two lobes. The bronchial tubes divide into smaller
air passages called bronchi, and then into bronchioles. The
bronchioles end in tiny air sacs called alveoli, where oxygen is transferred from the
inhaled air to the blood.
After absorbing oxygen, the blood leaves the lungs and is carried to the
heart. The blood then is pumped through your body to provide oxygen to the cells
of your tissues and organs. When cells use oxygen, carbon dioxide (CO2)
is produced and transferred to the blood. Your blood carries the CO2 back to
your lungs and it is removed when you exhale.
Your respiratory system prevents harmful substances from entering the lungs
by using:
- Cilia (small hairs) in your nose to help filter out
large particles;
- Mucus produced in the trachea and bronchial tubes to keep air
passages moist and aid in intercepting dust, bacteria and other substances;
and
- The sweeping motion of cilia to keep air passages clean. If
substances such as cigarette smoke are inhaled, the cilia stop functioning
properly.
References
American Lung Association. Your Lungs: How Lungs Work. http://www.lungusa.org/your-lungs/how-lungs-work Accessed 10/13/2010
U.S. Department of Health & Human Services. National Institutes of Health.
National Heart Lung and Blood Institute Diseases and Conditions Index. Lung
Diseases: How the Lungs Work. http://www.nhlbi.nih.gov/health/dci/Diseases/hlw/hlw_all.html
Accessed 10/13/2010