The respiratory system prevent harmful
substances in the air from entering the lungs using the following built-in
structures:
·
Hairs in your nose help filter out large particles.
·
Cilia (microscopic hairs), found along the air passages, move in
a sweeping motion to keep the air passages clean. They sweep in such a way that
they bring the particle toward the throat to be coughed out.
·
Mucus produced by cells
in the trachea and bronchus moisten the air passages. It also helps to trap
dust, bacteria and viruses, and other substances that were not trapped by the
hairs from entering the lungs.
·
With the aid of the cilia, impurities that reach the deeper
parts of the lungs are moved up via mucous and coughed out or swallowed.
·
The condition called bronchitis (inflammation of the bronchi) occurs
if harmful substances, such as cigarette smoke, are inhaled and the cilia stop
functioning properly.
