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Chapter 16
Lesson 3
Did You Know
Breathing is regulated by certain areas
of the brain that send impulses to
stimulate the automatic contraction of
the muscles involved in respiration.
Functions of the Respiratory
System
A. The main function of the respiratory system
is respiration – the exchange of gases
between the body and the environment.
B. Respiration has two parts:
1. External respiration is the exchange of oxygen
and carbon dioxide that takes place between air
and the blood in the lungs.
2. Internal respiration is the exchange of gases
between the blood and the body cells.
C. The continual exchange of gases in both the
external and internal respiration is essential for
survival.
Discussion Question
Why does the body need oxygen?
Structure of the Respiratory
System
A. The upper respiratory system included the nose and
throat; the lower respiratory system consists of the
lungs, larynx, trachea, and bronchi.
B. The lungs are the principal organs of the respiratory
system.
1. The lungs are in the chest, protected by the
ribs.
2. The diaphragm is the muscle that separated
the chest from the abdominal cavity.
3. Air moves into the lungs through the trachea,
or windpipe.
4. The trachea branches out into bronchi, the
main airways that reach into each lung.
Structure of the Respiratory
System
C. The breathing process is made possible when your
body creates a pressure difference between the lungs
and the outside of the body.
D. Air enters the body through the nose and mouth. It
passes through the pharynx, or throat, and then into
the trachea and then the bronchi.
E. The larynx, or voice box, connects the throat and the
trachea.
F. The epiglottis is a flap of cartilage above the larynx.
It fold down to keep food or drink from entering the
respiratory system.
Discussion Question
Why should you try to inhale through
your nose rather than through your
mouth?