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Respiratory System
Biol 105
Lecture 18
Chapter 14
Outline - Respiratory System
I.
II.
III.
IV.
Function of the respiratory system
Parts of the respiratory system
Mechanics of breathing
Regulation of breathing
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Respiratory system Function
 The function of the respiratory system is to
bring in oxygen to the body and remove
carbon dioxide.
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The Respiratory System
Breathing moves air
in and out of the lungs.
External respiration
is the exchange of
oxygen and carbon
dioxide between the
lungs and the blood.
Gas transport
moves oxygen and
carbon dioxide
between the lungs
and the body tissues.
Internal respiration is
the exchange of oxygen
and carbon dioxide
between blood and the
body tissues.
Oxygen
transport
Lungs
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Gas diffusion
Carbon
dioxide
transport
Gas diffusion
Tissue
Figure 14.1
This type of tissue covers and lines body parts
rv
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Connective
Epithelial
Muscle
Nervous
e
1.
2.
3.
4.
Cells lining respiratory tract
 Lined by pseudostratified ciliated columnar
epithelial cells. The cilia sweeps mucus,
germs and debris toward the throat.
 Mucus produced by goblet cells.
 Smoking damages the ciliated cells
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8-4
The Respiratory System
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Figure 14.4a
Ciliated cells in respiratory tract
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The Respiratory System
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Figure 14.3
The Respiratory System
UPPER RESPIRATORY
SYSTEM
• Filters, warms, and
moistens air
Sinuses
• Cavities in skull
• Lighten head
• Warm and moisten
air
Nasal cavity
• Produces mucus
• Filters, warms, and
moistens air
• Olfaction
Pharynx
• Passageway for
air and food
RESPIRATORY
MUSCLES
• Cause breathing
Intercostal
muscles
• Move ribs during
breathing
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Diaphragm
• Muscle sheet between
chest and abdominal
cavities with a role in
breathing
Figure 14.2 (1 of 2)
The Respiratory System
LOWER RESPIRATORY
SYSTEM
• Exchanges gases
Larynx
• Air passageway
• Prevents food and drink
from entering lower
respiratory system
• Produces voice
Bronchi
• Two branches of
trachea that conduct
air from trachea to
each lung
Bronchioles
• Narrow passageways
to conduct air from
bronchi to alveoli
Epiglottis
• Covers larynx during
swallowing
Lungs
• Structures that contain
alveoli and air
passageways
• Allow exchange of
oxygen and carbon
dioxide between
atmosphere and blood
Trachea
• Connects larynx with
bronchi leading to
each lung
• Conducts air to and
from bronchi
Alveoli
• Microscopic chambers
for gas exchange
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Figure 14.2 (2 of 2)
1. Nasal cavity
 Functions:
1. filters the air
2. warms the air
3. moisten the air entering the lungs
4. smell (which also plays a role in
the sense of taste)
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8-3
1. Nasal cavity
 Parts of the nasal cavity:
 Mucus membranes - secrete sticky mucus
to trap germs & debris.
 Contains olfactory receptor cells for the
sense of smell
 Sinuses – air filled cavities, warm and
moisten air
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8-3
2. Pharynx
 Functions - is a passageway for air,
liquids, and food. (swallowing begins
here). Connects the nasal cavity to the
esophagus and the larynx
 Tonsils are found here – lymphatic tissue
that protects against infection
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8-4
3. Larynx
 Functions
1. Connects the pharynx to the trachea
2. Contains vocal cords used to generate
sound
3. Prevents food from entering lower
respiratory tract
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8-4
3. Larynx
 Structure made from cartilage
 Epiglottis closes the trachea when
swallowing
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8-4
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4. Trachea
 Windpipe held open by concentric rings of
cartilage
 Function – Connects the larynx to the
bronchi.
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8-4
Bronchial Tree
Trachea leads to the bronchial tree:
5. Bronchi (bronchus)
6. Bronchioles
7. Alveoli (alveolus)
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8-4
The Respiratory System
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Figure 14.7
7. Alveoli
 Sacs at the end of the bronchioles, they are
surrounded by blood capillaries .
 Function: It is here that the oxygen diffuses
across the membrane into the capillaries, and
carbon dioxide goes from the capillaries to the
inside of the lungs.
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8-6
Alveoli
 Lungs - have about 300 million alveoli
 The structure of the alveoli increases
surface area of lung
 For alveoli to function properly they are
coated with phospholipid molecules called
surfactant that keep them open
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Alveoli
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Figure 14.8
The Respiratory System
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Table 14.1 (1 of 2)
The Respiratory System
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Table 14.1 (2 of 2)
What cells secrete mucus
cilliated columnar epi
goblet
squamous epi
osteocytes
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et
25% 25% 25% 25%
ep
i
1.
2.
3.
4.
The tube connecting the larynx to the primary
bronchi is
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25%
tra
pharynx
trachea
bronchioles
alveoli
yn
x
1.
2.
3.
4.
25%
Common passageway for air, food and drink
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25%
tra
pharynx
trachea
bronchioles
alveoli
yn
x
1.
2.
3.
4.
25%
Conducts air from the trachea to the bronchioles
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25%
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pharynx
trachea
bronchus
alveolus
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1.
2.
3.
4.
25%
Gas exchange takes place here
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25%
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pharynx
trachea
bronchioles
alveoli
yn
x
1.
2.
3.
4.
25%
Which cavity is the lung located in?
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Ab
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in
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abdominal
pericardial
pleural
dorsal
al
1.
2.
3.
4.
Inhalation
Inhalation
Rib cage
moves up
and out
Air flow
Intercostal
muscles
contract
Diaphragm
contracts
and flattens
The chest cavity increases
in size, and pressure within
the lungs decreases.
Diaphragm
contracts
The lungs expand, and
air moves in.
(a)
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Figure 14.9a
Inhalation
 When the diaphragm and intercostal muscles
contract, the volume of the thoracic cavity
increases, causing the pressure in the lungs to
decrease
 Inhalation is also called inspiration
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Exhalation
Exhalation
Air flow
Rib cage
moves down
and inward
Intercostal
muscles relax
Diaphragm
relaxes and
moves upward
The chest cavity decreases
in size, and pressure
within the lungs increases.
Diaphragm
relaxes
The lungs recoil,
and air moves out.
(b)
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Figure 14.9b
Exhalation
 Exhalation = Expiration
 When the same muscles relax, volume of
the thoracic cavity decreases, pressure in
the lungs increase
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Air Volumes
 The volume of air inhaled or exhaled
during a normal breath is called the tidal
volume
 Tidal volume is usually around 500 ml
 The volume of air moved into and out of
the lungs is an indication of health
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Air Volumes
 Inspiratory reserve volume = forced inhalation
volume
 Expiratory reserve volume = forced exhalation
volume
 Residual volume is the amount of air left in the
lungs after forced exhalation
 Vital capacity is the amount of air brought in
and out of the lungs during forced breathing
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Air Volumes
6000
Inspiratory
reserve
(forced
inhalation)
volume
Lung Volume (ml)
5000
4000
Total
lung
capacity
Vital
capacity
Tidal volume
3000
2000
Expiratory reserve
(forced exhalation)
volume
1000
Residual
volume
0
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Figure 14.10 (1 of 2)
Gas Exchanges in the Body
 Remember that O2 enters and CO2 leaves the
lungs = External respiration
 Then O2 and CO2 is exchanged between the
blood vessels and tissues = Internal Respiration
 This gas exchange is due to diffusion
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8-14
Oxygen Transport
 Oxygen is transported on Hemoglobin.
 When Oxygen is bound to hemoglobin, then it is
called Oxyhemoglobin
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8-15
Carbon Dioxide Transport
1. CO2 is transported dissolved in the plasma (10%)
2. CO2 is bound to hemoglobin (20%)
3. CO2 is converted to bicarbonate ions (70%)
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8-14
Bicarbonate ions
CO2 + H2O
Carbonic
anhydrase
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H2CO3
H+ + HCO3-
8-14
Diffusion of Gasses: Alveoli and Capillaries
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Figure 14.11 (2 of 2)
Diffusion of Gasses: Capillaries and Tissues
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Figure 14.11 (1 of 2)
Regulation of Breathing
 Normally we breath 12 - 15 ventilations per
minute.
 This rate is controlled by the medulla oblongata
region of the brain. Nerves transmit signal to the
diaphragm and muscles.
 Chemoreceptors in the medulla oblongata and
arteries detect levels of CO2 and O2 in the blood,
controlling the rate and depth of breathing.
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8-12
Important Concepts
 Read Ch 15
 What is the function of the respiratory system?
 What is the location and function of the all the
parts of the respiratory system?
 What are the parts of the nasal cavity and their
functions?
 What are the parts of the larynx and their
functions?
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Important Concepts
 What cell types lines the trachea, what are
their functions, be able to discus how
smoking effects this tissue?
 Where does the exchange of gases occur in
the lungs?
 What cavity contains the lungs?
 What controls the rate of breathing?
 Be able to discuss the mechanics of
breathing?
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Important Concepts
 How is oxygen carried in the blood?
 How is carbon dioxide carried in the blood,
know all the ways, and the which is the
predominate mode? (You don’t need to know
the chemical equation of bicarbonate
formation)
 What is the diaphragm and what is its
function?
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Definitions
 Goblet cells, sinuses, epiglottis, surfactant,
diaphragm, intercostal muscles,
Inhalation/inspiration, exhalation/expiration
tidal volume, inspiratory reserve volume,
expiratory reserve volume, residual volume,
vital capacity, hemoglobin, oxyhemoglobin,
chemoreceptors
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