Transcript Chapter 11: Respiratory System

UNIT B: Human Body Systems
Chapter 8: Human Organization
Chapter 9: Digestive System
Chapter 10: Circulatory System and
Lymphatic System
Chapter 11: Respiratory System:
Section 11.1
Chapter 12: Nervous System
Chapter 13: Urinary System
Chapter 14: Reproductive System
UNIT B Chapter 11: Respiratory System
Chapter 11: Respiratory System
In this chapter, you will learn about the
structure and function of the respiratory
system.
How would a narrowing and swelling of
the airways affect the respiratory
volumes?
How do the typical treatments for asthma
work to reduce the symptoms?
Asthma is a disease in which the airways
become constricted (narrowed) and inflamed
(swollen), both of which can result in difficulty
breathing. It is one of the most common
chronic diseases in children. It is estimated
that 10 to 15 percent of children in Canada
have asthma.
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Why is it so difficult to develop a cure for
asthma?
What are some of the normal defence
mechanisms of the respiratory tract?
UNIT B Chapter 11: Respiratory System
11.1 The Respiratory System
The main function of the respiratory
system is to allow oxygen from the air
to enter the blood and carbon dioxide
from the blood to exit into the air.
Ventilation, another term for breathing,
includes both inspiration (inhalation)
and expiration (exhalation).
• Air is conducted toward or away
from the lungs by a series of
cavities, tubes, and openings
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Section 11.1
UNIT B Chapter 11: Respiratory System
Section 11.1
The respiratory system works with the circulatory system in
the following homeostatic functions:
• External respiration: exchange of gases (oxygen and
carbon dioxide) between the air and blood
• Transport of gases to and from the lungs and tissues
• Internal respiration: exchange of gases between the blood
and tissue fluid
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UNIT B Chapter 11: Respiratory System
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Section 11.1
11.1 The respiratory tract. a. The respiratory tract extends from the nose to the lungs, which
are composed of air sacs called alveoli (see inset b). b. Gas exchange occurs between air in
the alveoli and blood within a capillary network that surrounds the alveoli. Notice that the
pulmonary arteriole is coloured blue—it carries O2-poor blood away from the heart to the
alveoli. Then carbon dioxide leaves the blood, and oxygen enters the blood. The pulmonary
venule is coloured red—it carries O2-rich blood from the alveoli toward the heart.
UNIT B Chapter 11: Respiratory System
Section 11.1
The Respiratory Tract
Inspiration: air is filtered, warmed, and moistened as it moves
along the respiratory tract
• Filtered by hairs in the nostrils, and by cilia in the mucus of
nasal cavities and airways
• Warmed by heat given off by blood vessels close to the lining
of the airways
• Moistened by the wet surface of airways
Expiration: air cools and loses its moisture as it moves out of the
respiratory tract
• Deposits moisture on the lining of the trachea and nose
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UNIT B Chapter 11: Respiratory System
Figure 11.2 Ciliated Cells. These cells line the interior of the nasal
passages and upper respiratory tract.
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Section 11.1
UNIT B Chapter 11: Respiratory System
Section 11.1
The Nose
The nose is the only external
portion of the respiratory system.
• Air enters the nose through
the nostrils
• Air is moistened and warmed
in two nasal cavities that are
lined with mucous
membranes
• Nasal cavities are separated
from the mouth by the palate,
which is composed of the
hard palate and soft palate
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Figure 11.3 The path of air. Air passes through
the nasal cavities and mouth to and from the
upper and lower respiratory tracts. The trachea
is part of the lower respiratory tract; the other
organs are in the upper respiratory tract.
UNIT B Chapter 11: Respiratory System
The Pharynx
The pharynx is also known as
the “throat.”
• Connects the nasal and oral
cavities to the larynx
• Contains lymphatic tissues
called tonsils that contain
lymphocytes that protect
against pathogens
• Allows for the passage of
air and food
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Section 11.1
UNIT B Chapter 11: Respiratory System
The Larynx
The larynx is called the voice box
since it contains the vocal cords.
• Connects the pharynx to the
trachea
• Composed of cartilage and
dense connective tissue
• Allows for the passage of air
(the glottis allows air into the
larynx)
• A flap of tissue above the
larynx, the epiglottis, prevents
passage of food into lower
respiratory tract
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Section 11.1
UNIT B Chapter 11: Respiratory System
Figure 11.4 Placement of the vocal cords. Viewed from above, the vocal
cords stretch across the glottis, the opening to the trachea. When air is
expelled through the glottis, the vocal cords vibrate, producing sound. The
glottis is narrow when we make a high-pitched sound, and it widens as the
pitch deepens.
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Section 11.1
UNIT B Chapter 11: Respiratory System
The Trachea
The trachea is commonly called the
windpipe.
• Connects larynx with bronchi
• Composed of C-shaped
cartilaginous rings
• Allows for the passage of air to
bronchi
• Cleans, warms, and moistens air
• Mucous membrane lining
contains goblet cells (produce
mucus) and ciliated cells (sweep
mucus and debris toward the
pharynx)
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Section 11.1
UNIT B Chapter 11: Respiratory System
Figure 11.5 The surface of the trachea. A scanning electron micrograph
shows that the surface of the mucous membrane lining the trachea consists
of goblet cells and ciliated cells. The cilia sweep mucus and the debris
embedded in it toward the pharynx, where they are swallowed or
expectorated. Smoking causes the cilia to disappear, allowing debris to
enter the bronchi and lungs.
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Section 11.1
UNIT B Chapter 11: Respiratory System
The Bronchial Tree
The trachea divides into the
bronchi, which lead into the lungs.
• The bronchi branch into
secondary bronchi that lead to
bronchioles
• Each bronchiole leads to thinwalled air sacs called alveoli (site
of gas exchange between air and
blood)
• The components of the bronchial
tree beyond the primary bronchi
make up the lungs
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Section 11.1
UNIT B Chapter 11: Respiratory System
The Lungs
The lungs are paired, cone-shaped
organs that contain alveoli, airways,
and blood vessels.
• At the base of the lungs is the
diaphragm, a muscle involved in
inspiration and expiration
• Each lung is covered with a thin
membrane called a pleura
o Secretes fluid so that it can
slide freely against the pleura
of the chest wall and
diaphragm during inspiration
and expiration
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Section 11.1
UNIT B Chapter 11: Respiratory System
The Lungs
• During inhalation, air enters the
lungs by way of the bronchial
tree and moves to the alveoli
• Gas exchange occurs between
the air in an alveolus and the
blood in the capillaries
o Alveoli are covered with
pulmonary surfactant, a film
of lipoprotein that prevents
the alveoli from closing so
that inhaled air can enter
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Section 11.1
UNIT B Chapter 11: Respiratory System
Section 11.1
Figure 11.6 Gas exchange in the lungs.
The lungs consist of portions of the
bronchial tree leading to the alveoli. Each
alveolus is surrounded by an extensive
capillary network. Notice that the pulmonary
artery and arteriole carry O2-poor blood
(coloured blue) and the pulmonary vein and
venule carry O2-rich blood (coloured red).
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UNIT B Chapter 11: Respiratory System
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Section 11.1
UNIT B Chapter 11: Respiratory System
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Section 11.1
UNIT B Chapter 11: Respiratory System
Check Your Progress
1. List the structures of the respiratory system.
2. Describe how the arrangement of the trachea,
esophagus, larynx, and epiglottis prevents food from
entering the trachea.
3. Describe the function of pulmonary surfactant.
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Section 11.1
UNIT B Chapter 11: Respiratory System
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Section 11.1