4. How do your lungs work?
The contraction and relaxation of your diaphragm controls the
movement of your lungs. When the diaphragm contracts, it becomes
flatter, the pressure in the chest cavity is reduced and the lungs
expand resulting in rushing of air into them. At the same time, the
rib muscles contract lifting the ribs upwards and outwards.
When the diaphragm and the ribs relax, the lungs shrink and force
the air out (breathing out). Air is breathed in through the mouth and
nose.
It passes through the windpipe or trachea. The trachea is divided
into two bronchial tubes that are further divided into a number of
smaller tubes called bronchioles. These finally end into air sacs called
alveoli, which are surrounded by a network of blood capillaries.
When air reaches these alveoli, the oxygen of the air is absorbed by
the blood. Waste carbon dioxide passes from the blood into the
alveoli and is breathed out.
