NCCN Guidelines for Patients
: Non-Small Cell Lung Cancer
Part 1: About lung cancer
1.1 Parts of the lungs
The lungs are the main organs of the respiratory system.
They transfer oxygen—a gas that cells need to live—from
the air into the blood. The blood then carries oxygen to
all the cells in the body. The lungs also remove carbon
dioxide—a gas made by cells—from the blood. Carbon
dioxide is then exhaled from the lungs into the air. The
transfer of these gases in and out of the body is called
When you inhale, air enters the mouth or nose and
travels down the throat into the trachea. See Figure 1.
Air then enters the lungs through the bronchi. Within
the lung, the bronchi branch off to each part (lobe) of the
lung. The right lung has three lobes and the left lung has
only two lobes to make space for the heart.
Within the lobes, the bronchi divide into smaller airways
called bronchioli. At the end of each bronchioli are
bunches of alveoli wrapped in blood vessels. The transfer
of gases in and out of the blood occurs in the alveoli.
The lungs are protected by tissue called the pleura.
Pleura covers each lung and helps the lungs safely rub
against other organs. Pleura is made of two layers. The
outer layer is known as the parietal pleura. The inner
layer is called the visceral pleura. The space in between
the two layers is called the pleural cavity. It is filled with a
small amount of fluid called pleural fluid.
Figure 1. Airways and the lungs
Illustration Copyright © 2013 Nucleus Medical Media, All rights reserved.