Your lungs’ main job is to make oxygen available to your body
and to remove other gases, such as carbon dioxide. This process is done 12 to 20
times per minute.
When you inhale air through your nose or mouth, it travels down
the back of your throat (pharynx), passes through your voice box (larynx) and
into your windpipe (trachea).
Your trachea is divided into two air passages (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 as you breathe in
(inhalation) and breathe out (exhalation), and free from inflammation (swelling)
and excess (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 (bronchi), and then into bronchioles. The bronchioles end
in tiny air sacs called alveoli, where oxygen and carbon dioxide are exchanged.
After absorbing oxygen, the blood leaves the lungs and is
carried to the heart. Then, it is pumped through your body to provide oxygen to
the cells of your tissues and organs. When the oxygen is used by the cells,
carbon dioxide (CO2) is produced and transferred to the blood. Your blood
carries the CO2 back to your lungs and removes it when you exhale.
The respiratory system has built-in methods to prevent harmful
substances from entering the lungs:
- The hair (cilia) in your nose helps filter out large particles.
- Mucus produced by cells in the trachea and bronchial tubes keeps air
passages moist and aids in trapping dust, bacteria, and other substances.
- Cilia in the air passages move in a sweeping motion to keep the air
passages clean. If substances such as cigarette smoke are inhaled, the cilia
stop functioning properly.
Healthy lungs are made of a spongy, pinkish-gray tissue. Lungs
that have become polluted with harmful carcinogens (substances that can cause
cancer) or carbon particles appear to have blackened spots on the surface.
Healthy lungs are elastic so they can expand when you inhale.
In contrast, a disease like emphysema causes the lungs to lose
their elasticity.
When a lung can no longer expand properly or transfer oxygen to
the blood, that person has difficulty breathing and tires easily. Other
difficulties might occur because the tissues and organs aren’t getting the
oxygen they need.