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Chapter 10
Lecture Outline
See separate PowerPoint slides for all figures and tables pre-
inserted into PowerPoint without notes.
Copyright © 2016 McGraw-Hill Education. Permission required for reproduction or display.
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Respiratory System
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Points to ponder
• What are the parts and functions of the upper and lower respiratory system?
• What is the mechanism for expiration and inspiration?
• How is breathing controlled by the nervous system and through chemicals?
• Where and how is exchange of gases accomplished?
• What are some common respiratory infections and disorders?
• What do you know about tobacco and health?
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Overview of the respiratory system 10.1 The Respiratory System
Upper Respiratory Tract
Lower Respiratory Tract
Nasal cavity filters, warms, and moistens air
Pharynx passage way where pathway for air and food cross
Glottis space between the vocal chords; opening to larynx
Larynx (voice box) ; produces sound
Trachea (wind pipe) ; passage of air to bronchi
Bronchus passage of air to lungs
Diaphragm skeletal muscle; functions in ventilation
Lung contains alveoli (air sacs); carries out gas exchange
Bronchioles passage of air to alveoli
Figure 10.1 The human respiratory tract.
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What is the pathway that air follows?
nose
pharynx
larynx
trachea
bronchus
bronchioles
alveoli
10.1 The Respiratory System
6
What constitutes the upper respiratory
tract?
• Nose
• Pharynx
• Larynx
10.2 The Upper Respiratory Tract
sinus
Pharynx
nasopharynx
oropharynx
laryngo-
pharynx
esophagus
tonsil
sinus
nasal cavity
hard
palate
nares
uvula
mouth
tongue
tonsils
epiglottis
glottis
larynx
trachea
Figure 10.2 The upper respiratory tract.
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The nose
• The nose opens at the nostrils/nares and leads into the nasal cavities.
• Hairs and mucus in the nose filter the air.
• The nasal cavity has a lot of capillaries that warm and moisten the air.
• Specialized cells act as odor receptors.
• Tear glands drain into the nasal cavities that can lead to a runny nose.
10.2 The Upper Respiratory Tract
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The pharynx
• The pharynx is a funnel-shaped cavity commonly called the throat.
• It has three portions based on location: nasopharynx, oropharynx, and laryngopharynx.
• Tonsils provide a lymphatic defense during breathing at the junction of the oral cavity and pharynx.
10.2 The Upper Respiratory Tract
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The larynx
• The larynx is a triangular, cartilaginous structure that passes air between the pharynx and trachea.
• It is called the voice box and houses vocal cords.
• There are two mucosal folds that make up the vocal cords with an opening in the middle called the glottis.
10.2 The Upper Respiratory Tract
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The larynx
Figure 10.4 The vocal cords.
10.2 The Upper Respiratory Tract
(left): © CNRI Phototake
base of
tongue
epiglottis
glottis
vocal
cords
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What constitutes the lower respiratory
tract?
• Trachea
• Bronchial
tree
• Lungs
10.3 The Lower Respiratory Tract
Upper Respiratory Tract
Lower Respiratory Tract
Nasal cavity filters, warms, and moistens air
Pharynx passage way where pathway for air and food cross
Glottis space between the vocal chords; opening to larynx
Larynx (voice box) ; produces sound
Trachea (wind pipe) ; passage of air to bronchi
Bronchus passage of air to lungs
Diaphragm skeletal muscle; functions in ventilation
Lung contains alveoli (air sacs); carries out gas exchange
Bronchioles passage of air to alveoli
Figure 10.1 The human respiratory tract.
12
The trachea
• The trachea is a tube, often called the
windpipe, that connects the larynx with the
primary bronchi.
• It is made of connective tissue, smooth
muscle, and cartilaginous rings.
• The trachea is lined with cilia and mucus that
help to keep the lungs clean.
10.3 The Lower Respiratory Tract
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The trachea
Figure 10.5 The cells lining the trachea.
10.3 The Lower Respiratory Tract
tracheal
lumen
air
mucus
particle
movement
epithelial
cell
goblet cell
cilia
(bottom half): © ED Reschke
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The bronchial tree
• The bronchial tree starts with two main bronchi that lead from the trachea into the lungs.
• The bronchi continue to branch until they are small bronchioles about 1 mm in diameter with thinner walls.
• Bronchioles eventually lead to elongated sacs called alveoli.
10.3 The Lower Respiratory Tract
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The lungs
• The secondary bronchi, bronchioles, and
alveoli make up the lungs.
• The right lung has three lobes while the left
lung has two lobes.
• Each lobe is divided into lobules.
• Each lung is enclosed by membranes called
pleura.
10.3 The Lower Respiratory Tract
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The alveoli
• There are 300 million alveoli in the lungs that greatly increase surface area.
• Alveoli are enveloped by blood capillaries.
• The alveoli and capillaries are one layer of epithelium to allow exchange of gases.
• Alveoli are lined with surfactant that act as a film to keep alveoli open.
10.3 The Lower Respiratory Tract
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The alveoli
Figure 10.6 Pulmonary circulation to and from the lungs.
10.3 The Lower Respiratory Tract
alveoli
capillary
network
lobule
bronchiole
blood flow blood flow
pulmonary vein
pulmonary artery
Pulmonary arteriole
contains much CO2, little O2.
Pulmonary venule
contains much O2,
little CO2
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Two phases of
breathing/ventilation 1. Inspiration – an active process of inhalation
that brings air into the lungs
2. Expiration – a typically passive process of
exhalation that expels air from the lungs
10.4 Mechanism of Breathing
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Boyle’s Law
• Ventilation is
governed by Boyle’s
Law.
• At a constant
temperature the
pressure of a given
quantity of gas is
inversely proportional
to its volume.
10.4 Mechanism of Breathing
Figure 10.7 The relationship between air pressure
and volume.
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Inspiration
• The diaphragm and intercostal muscles contract.
• The diaphragm flattens and the rib cage moves
upward and outward.
• Volume of the thoracic cavity and lungs increase.
• The air pressure within the lungs decreases.
• Air flows into the lungs.
10.4 Mechanism of Breathing
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Inspiration
Figure 10.8a The thoracic cavity during inspiration.
10.4 Mechanism of Breathing
a. Inspiration
Rib cage
moves
up and out.
lungs
lung
rib cage
Diaphragm
contracts
and moves down.
When
Pressure
in lungs
decreases,
air comes
rushing in.
trachea
air in
External intercostal
muscles
pull the ribs outward.
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Expiration
• The diaphragm and intercostal muscles relax.
• The diaphragm moves upward and becomes dome-shaped.
• The rib cage moves downward and inward.
• Volume of the thoracic cavity and lungs decreases.
• The air pressure within the lungs increases.
• Air flows out of the lungs.
10.4 Mechanism of Breathing
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Expiration
Figure 10.8b The thoracic cavity during expiration.
10.4 Mechanism of Breathing
b. Expiration
Internal intercostal muscles
pull the ribs inward during
forced expiration.
Rib cage
moves
down and
in.
Diaphragm relaxes
and moves up.
When
pressure
in lungs
increases,
air is
pushed out.
air out
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Different volumes of air during
breathing • Tidal volume – the small amount of air that usually
moves in and out with each breath
• Vital capacity – the maximum volume of air that can be moved in plus the maximum amount that can be moved out during one breath
• Inspiratory and expiratory reserve volume – the increased volume of air moving in or out of the body
• Residual volume – the air remaining in the lungs after exhalation
10.4 Mechanism of Breathing
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Visualizing the vital capacity
5,800
4,800
3,600
2,900
2,400
1,200
0
Avera
ge L
un
g V
olu
me (
ml)
maximum
inspiration
maximum
expiration inspiratory
reserve
volume
tidal
volume
expiratory
reserve
volume
residual
volume
residual
volume
vital
capacity total
Lung
capacity
© Veronique Burger/Science Source
Figure 10.9 Measuring the vital capacity of the lungs.
10.4 Mechanism of Breathing
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• Nervous control
– Respiratory control center in the brain
(medulla oblongata) sends out nerve
impulses to contract muscle for inspiration.
– Sudden infant death syndrome (SIDS) is
thought to occur when this center stops
sending out nerve signals.
10.5 Control of Ventilation
How is breathing controlled by
the nervous system?
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How is breathing controlled by
the nervous system?
10.5 Control of Ventilation
brain
Respiratory center:
region of the brain that
automatically regulates
breathing
Intercostal nerves
stimulate the intercostal
muscles to contract.
External intercostal muscles
help expand the thoracic
cavity by contracting.
Phrenic nerve
stimulates the diaphragm
to contract.
Diaphragm
helps expand the thoracic
cavity by flattening when
it contracts.
Figure 10.10 The control of
breathing by the respiratory center.
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How is breathing chemically
controlled?
• Chemical control
– Two sets of chemoreceptors sense the
drop in pH: one set is in the brain and the
other in the circulatory system.
– Both are sensitive to carbon dioxide levels
that change blood pH due to metabolism.
10.5 Control of Ventilation
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Exchange of gases in the body
• Oxygen and carbon dioxide are exchanged.
• The exchange of gases is dependent on diffusion.
• Partial pressure is the amount of pressure each gas exerts (PCO2
or PO2).
• Oxygen and carbon dioxide will diffuse from the area of higher to the area of lower partial pressure.
10.6 Gas Exchanges in the Body
30
External respiration
• Exchange of gases between the lung alveoli and the blood capillaries.
• PCO2 is higher in the lung capillaries than the
air, thus CO2 diffuses out of the plasma into the lungs.
• The partial pressure pattern for O2 is just the opposite, so O2 diffuses the red blood cells in the lungs.
10.6 Gas Exchanges in the Body
31
External respiration
Carbon dioxide transport: carbonic
H+ + HCO3- H2CO3
anhydrase H2O + CO2
Oxygen transport:
Hb + O2 HbO2
10.6 Gas Exchanges in the Body
32
The movement of oxygen and
carbon dioxide in the body
pulmonary artery pulmonary vein
lung
External respiration
Internal respiration
heart
systemic vein systemic artery tissue cells
CO2
H+ HCO–3
CO2
O2
O2
Hb H+
Hb
Hb
Hb
+
alveolus
alveolus
plasma
plasma
plasma
pulmonary
capillary
pulmonary
capillary
a.
RBC
CO2
plasma
RBC
RBC
RBC
tissue
cell
tissue
cell
tissue
fluid
tissue
fluid
systemic
capillary
systemic
capillary
CO2 exits blood
CO2
HCO–3
CO2
H2O
H2CO3
O2 CO2
O2
O2 enters blood
O2
O2 exits blood
b.
CO2 enters blood
H+ HCO–3
Hb H+
Hb
+
CO2
H2O
H2CO3
HCO–3
Figure 10.11
Movement of gases
during external and
internal respiration.
10.6 Gas Exchanges in the Body
33
Internal respiration
• The exchange of gases between the blood in
the capillaries outside of the lungs and the
tissue fluid.
• PO2 is higher in the capillaries than the tissue
fluid, thus O2 diffuses out of the blood into
the tissues.
10.6 Gas Exchanges in the Body
34
Internal respiration
Oxyhemoglobin gives up oxygen:
HbO2 Hb + O2
Most CO2 is carried as a bicarbonate ion: carbonic
CO2 + H2O anhydrase H2CO3 H
+ + HCO3-
10.6 Gas Exchanges in the Body
35
Upper respiratory tract
infections
• Sinusitis – blockage of sinuses
• Otitis media – infection of the middle ear
• Tonsillitis – inflammation of the tonsils
• Laryngitis – infection of the larynx that leads to loss of voice
10.7 Respiration and Health
36
Lower respiratory tract disorders
• Pneumonia – infection of the lungs with thick,
fluid build up
• Tuberculosis – bacterial infection that leads to
tubercles (collections of encapsulated bacteria)
• Pulmonary fibrosis – lungs lose elasticity
because fibrous connective tissue builds up in
the lungs, usually because of inhaled particles
10.7 Respiration and Health
37
Lower respiratory tract disorders
• Emphysema – chronic, incurable disorder in which alveoli are damaged, and thus the surface area for gas exchange is reduced
• Asthma – bronchial tree becomes irritated causing breathlessness, wheezing, and coughing
• Lung cancer – uncontrolled cell division in the lungs that is often caused by smoking and can lead to death
10.7 Respiration and Health
38
Some Diseases and Disorders
of the Respiratory System
Pneumonia
Alveoli fill with pus and fluid,
making gas exchange difficult.
Bronchitis
Airways are inflamed due
to infection (a cute) or due to
an irritant (chronic). Coughing
brings up mucus and pus.
mucus
Asthma
Airways are inflamed due
to irritation, and bronchioles
constrict due to muscle spasms.
asbestos
body
Emphysema
Alveoli burst and fuse into
enlarged air spaces. Surface area
for gas exchange is reduced.
Pulmonary Tuberculosis
Tubercles encapsulate
bacteria, and elasticity of
lungs is reduced.
Pulmonary Fibrosis
Fibrous connective tissue
builds up in lungs, reducing
their elasticity.
tubercle
Figure 10.12 Some diseases and disorders of the respiratory system.
10.7 Respiration and Health
39
Things you should know about
tobacco and health
• All forms of tobacco can cause damage.
• Smoking increases a person’s chance of lung, mouth, larynx, esophagus, bladder, kidney, pancreatic, stomach, and cervix cancers.
• Smoking also increases the chance of chronic bronchitis, emphysema, heart disease, stillbirths, and harm to an unborn child.
• Passive smoke can increase a nonsmoker’s chance of pneumonia, bronchitis, and lung cancer.
10.7 Respiration and Health
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