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Chapter 37
Respiratory
Systems
Outline
Gas Exchange Surfaces
Water Environments
- Gills
Land Environments
- Lungs
Human Respiratory System
Inspiration versus Expiration
Respiration and Health
Respiratory Disorders
Respiratory
Systems
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Gas Exchange Surfaces
Respiratory
Systems
Respiration:
The events associated with gas exchange
between the cells and the external environment
Consists of
- Ventilation
- External Respiration
- Internal Respiration
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Gas Exchange Surfaces
Respiratory
Systems
For diffusion to be effective, gas-exchange
regions must be:
Moist
Thin
Relatively large
Effectiveness of diffusion is enhanced by
vascularization
Delivery to cells is promoted by respiratory
pigments (like hemoglobin)
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Water Environments
Respiratory
Systems
Gasses of air can dissolve in water
However
When saturated, water contains small fraction of
the O2 in same volume of air, and
Water is much more viscous than air
Aquatic animals expend more energy to breathe
than do terrestrial animals
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Gas Exchange
Respiratory
Systems
Hydras and planarians
Small animals with large surface area
Most of their cells exchange gases directly with
the environment
Larger aquatic animals
Often have gills
- Finely divided vascularized outgrowths of inner
body surface
- Gills of bony fishes
 Outward
extensions of pharynx
 Ventilation is brought about by combined action of
the mouth and gill covers (operculum)
Countercurrent Exchange
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Animal Shapes and Gas Exchange
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Anatomy of Gills in Bony Fishes
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Land Environments:
Tracheae
Respiratory
Systems
Insects and other terrestrial arthropods
A respiratory system consists of branched
tracheae
Oxygen enters tracheae at spiracles
Tracheae branch until end in tracheoles that are
in direct contact with body cells
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Tracheae of Insects
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Land Environments:
Lungs of Vertebrates
Respiratory
Systems
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Terrestrial vertebrates have evolved lungs
Vascular outgrowths from lower pharyngeal region
Lungs of amphibians
- Possess a short tracheae which divides into two bronchi that
open into lungs
- Many also breathe to some extent through skin
Reptiles
- Inner lining of lungs is more finely divided in reptiles than in
amphibians
Lungs of birds and mammals are elaborately subdivided
All terrestrial vertebrates, except birds, use a tidal
ventilation system
Air moves in and out by the same route
Ventilation in Frogs
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Ventilation in
Terrestrial Vertebrates
Respiratory
Systems
Inspiration in mammals
Create negative pressure in lungs
The rib cage is elevated
The diaphragm lowers
Thoracic pressure decreases to less than atmospheric
pressure
Atmospheric pressure forces air into the lungs
Expiration in mammals
Create positive pressure in lungs
The rib cage is lowered
The diaphragm rises
Thoracic pressure increases to more than atmospheric
pressure
Forces air out the lungs
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Lungs
Respiratory
Systems
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Birds use a one-way ventilation mechanism in
lungs
Results in a higher partial pressure of oxygen in
the lungs
Oxygen uptake with each breath is greater than in
other vertebrates
Respiratory System in Birds
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Human Respiratory System
Respiratory
Systems
As air moves through upper respiratory system
It is filtered to free it of debris
Warmed, and
Humidified
When air reaches lungs
It is at body temperature, and
Its humidity is 100%
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The Human Respiratory Tract
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Human Respiratory System
Respiratory
Systems
Air passes from pharynx through glottis
Larynx and trachea
Permanently held open by cartilage rings
Facilitates movement of air
When food is swallowed
The larynx rises, and
The glottis is closed by the epiglottis
Backward movement of soft palate covers the
entrance of nasal passages into the pharynx
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Human Respiratory System
Respiratory
Systems
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Trachea divides
Forms two primary bronchi
Bronchi enter the right and left lungs
Bronchi branch until there are a great number of
tiny bronchioles
Each bronchiole terminates in an elongated
space enclosed by alveoli
Ventilation
Respiratory
Systems
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Humans breathe using a tidal mechanism
Volume of thoracic cavity and lungs is increased
by muscle contractions that lower the diaphragm
and raise the ribs
- Create negative pressure in the thoracic cavity and
lungs, and then air flows into the lungs during
inspiration
Inspiration Versus Expiration
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External and Internal respiration
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Hemoglobin
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Gas Exchange and Transport
Respiratory
Systems
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Breathing stimulus
Increased H+ and CO2 concentrations in the
blood
Not affected by O2 levels
Oxygen diffuses into pulmonary capillaries
Most combines with hemoglobin in red blood cells
to form oxyhemoglobin
CO2 diffuses out of pulmonary capillaries
Most carbon dioxide is transported in the form of
bicarbonate ion
Some carbon dioxide combines with hemoglobin
to form carbaminohemoglobin
Hemoglobin Saturation
in Relation to Temperature and Acidity
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Respiration and Health
Upper Respiratory Tract Infections
Strep Throat
- Streptococcus pyogenes
Sinusitis
- Infection of sinuses
Tonsillitis
- Infection of tonsils
Laryngitis
- Infection of larynx
Respiratory
Systems
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Common
Bronchial and Pulmonary Diseases
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Respiration and Health
Respiratory
Systems
Lower Respiratory Tract Infections
Acute bronchitis
- Infection of primary and secondary bronchi
Pneumonia
- Viral or bacterial infection of the lungs where
bronchi and alveoli fill with fluid
Pulmonary tuberculosis
- Caused by tubercle bacillus
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Disorders
Respiratory
Systems
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Pulmonary fibrosis
Fibrous connective tissue builds up in the lungs
Chronic bronchitis
Airways inflamed and filled with mucus
Emphysema
Alveoli are distended and walls are damaged
reducing surface area available for gas exchange
Disorders
Respiratory
Systems
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Asthma
Airways are unusually sensitive to specific
irritants
- When exposed to the irritants, the smooth muscles
in the bronchioles undergo spasms
Lung Cancer
Begins with thickening and callusing of the cells
lining the airways
Review
Gas Exchange Surfaces
Water Environments
- Gills
Land Environments
- Lungs
Human Respiratory System
Inspiration versus Expiration
Respiration and Health
Respiratory Disorders
Respiratory
Systems
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Ending Slide Chapter 37
Respiratory
Systems