|Each body has two lungs, one on the right side and
one on the left side of the chest. Each lung is about
25-30 cm. long, and the lungs lie in the chest under the
ribs. The right lung is on the right side of the chest
and is divided into three sections called lobes. The left
lung is on the left side of the chest and has two lobes.
The two lungs are separated by a structure called the
mediastinum. This contains the heart, trachea, esophagus
and blood vessels. This mediastinum is covered by the
breast bone which connects to the ribs which provides a
hard, bony covering to protect the heart and lungs. The
left lung is smaller than the right lung because of the
room needed in the chest cavity for the heart.
Inspiration, or breathing in, refers to the movement of air into the lungs. When air is pulled in through the nose and mouth it enters the trachea, then moves down to the broncus which divides into the left and right bronchial tubes. Each bronchial tube carries air into the lungs where it is divided into little air sacks called alveoli. The blood flows into the lungs through capillaries, or little tiny veins. These veins carry blood that is high in carbon dioxide and other waste gasses, that the body needs to get rid of, while the alveoli hold oxygen rich air. The carbon dioxide and the oxygen trade places and the "bad air" full of waste gasses is pushed out of the nose and mouth in a process called expiration. While the "good air" full of oxygen goes into the blood to be circulated to all the cells of the body.
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This page lasted edited on 03/31/98