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13
PART A
The Respiratory
System
PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University
ESSENTIALS
OF HUMAN
ANATOMY
& PHYSIOLOGY
EIGHTH EDITION
ELAINE N. MARIEB
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Organs of the Respiratory system
1. Nose
2. Pharynx
3. Larynx
4. Trachea
5. Bronchi
6. Lungs –
alveoli
Figure 13.1
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Function of the Respiratory System
A. Oversees gas exchanges between the blood
and external environment
B. Exchange of gasses takes place within the
lungs in the alveoli
C. Passageways to the lungs purify, warm,
and humidify the incoming air
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The Nose
1. The only externally visible part of the
respiratory system
2. Air enters the nose through the external
nares (nostrils)
3. The interior of the nose consists of a nasal
cavity divided by a nasal septum
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Upper Respiratory Tract
Figure 13.2
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Anatomy of the Nasal Cavity
A. Olfactory receptors are located in the
mucosa on the superior surface
B. The rest of the cavity is lined with
respiratory mucosa
1. Moistens air
2. Traps incoming foreign particles
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Anatomy of the Nasal Cavity
C. Lateral walls have projections called
conchae
1. Increases surface area
2. Increases air turbulence within the nasal
cavity
D. The nasal cavity is separated from the oral
cavity by the palate
1. Anterior hard palate (bone)
2. Posterior soft palate (muscle)
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Paranasal Sinuses
A. Cavities within bones surrounding the
nasal cavity
1. Frontal bone
2. Sphenoid bone
3. Ethmoid bone
4. Maxillary bone
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Paranasal Sinuses
B. Function of the sinuses
1. Lighten the skull
2. Act as resonance chambers for speech
3. Produce mucus that drains into the nasal
cavity
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Pharynx (Throat)
A. Muscular passage from nasal cavity to larynx
B. Three regions of the pharynx
1. Nasopharynx – superior region behind nasal
cavity
2. Oropharynx – middle region behind mouth
3. Laryngopharynx – inferior region attached to
larynx
C. The oropharynx and laryngopharynx are common
passageways for air and food
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Structures of the Pharynx
A. Auditory tubes enter the nasopharynx
B. Tonsils of the pharynx
1. Pharyngeal tonsil (adenoids) in the
nasopharynx
2. Palatine tonsils in the oropharynx
3. Lingual tonsils at the base of the tongue
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Larynx (Voice Box)
A. Routes air and food into proper channels
B. Plays a role in speech
C. Made of eight rigid hyaline cartilages and
a spoon-shaped flap of elastic cartilage
(epiglottis)
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Structures of the Larynx
1. Thyroid cartilage
Largest hyaline cartilage
Protrudes anteriorly (Adam’s apple)
2. Epiglottis
Superior opening of the larynx
Routes food to the larynx and air toward
the trachea
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Structures of the Larynx
3. Vocal cords (vocal folds)
Vibrate with expelled air to create sound
(speech)
4. Glottis – opening between vocal cords
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Trachea (Windpipe)
A. Connects larynx with bronchi
B. Lined with ciliated mucosa
Beat continuously in the opposite direction
of incoming air
Expel mucus loaded with dust and other
debris away from lungs
C. Walls are reinforced with C-shaped hyaline
cartilage
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Primary Bronchi
A. Formed by division of the trachea
B. Enters the lung at the hilus
(medial depression)
C. Right bronchus is wider, shorter,
and straighter than left
D. Bronchi subdivide into smaller
and smaller branches
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Lungs
Occupy most of the thoracic cavity
A. Apex is near the clavicle (superior
portion)
Base rests on the diaphragm (inferior
portion)
B. Each lung is divided into lobes by
fissures
Left lung – two lobes
Right lung – three lobes
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Lungs
Figure 13.4b
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Coverings of the Lungs
1. Pulmonary (visceral) pleura covers the
lung surface
2. Parietal pleura lines the walls of the
thoracic cavity
Pleural fluid fills the area between layers
of pleura to allow gliding
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Respiratory Tree Divisions
1. Primary bronchi
2. Secondary bronchi
3. Tertiary bronchi
4. Bronchioli
5. Terminal bronchioli
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Bronchioles
A. Smallest
branches of
the bronchi
Figure 13.5a
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Bronchioles
B. All but
the smallest
branches
have
reinforcing
cartilage
Figure 13.5a
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Bronchioles
C. Terminal
bronchioles
end in alveoli
Figure 13.5a
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Respiratory Zone
A. Structures
1. Respiratory bronchioli
2. Alveolar duct
3. Alveoli
B. Site of gas exchange
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Alveoli
A. Structure of alveoli
1. Alveolar duct
2. Alveolar sac
3. Alveolus
B. Gas exchange takes place within the
alveoli in the respiratory membrane
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Respiratory Membrane (Air-Blood Barrier)
A. Thin squamous epithelial layer lining
alveolar walls
B. Pulmonary capillaries cover external
surfaces of alveoli
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Respiratory Membrane (Air-Blood Barrier)
Figure 13.6
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Gas Exchange
A. Gas crosses the respiratory membrane by
diffusion
1. Oxygen enters the blood
2. Carbon dioxide enters the alveoli
B. Macrophages add protection
C. Surfactant coats gas-exposed alveolar
surfaces
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Events of Respiration
A. Pulmonary ventilation – moving air in and
out of the lungs
B. External respiration – gas exchange
between pulmonary blood and alveoli
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Events of Respiration
C. Respiratory gas transport – transport of
oxygen and carbon dioxide via the
bloodstream
D. Internal respiration – gas exchange
between blood and tissue cells in systemic
capillaries
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Mechanics of Breathing (Pulmonary
Ventilation)
A. Completely mechanical process
B. Depends on volume changes in the
thoracic cavity
C. Volume changes lead to pressure changes,
which lead to the flow of gases to equalize
pressure
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Mechanics of Breathing (Pulmonary
Ventilation)
D. Two phases
1. Inspiration – flow of air into lung
2. Expiration – air leaving lung
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Inspiration
1. Diaphragm and intercostal muscles
contract
2. The size of the thoracic cavity increases
3. External air is pulled into the lungs due to
an increase in intrapulmonary volume
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Inspiration
Figure 13.7a
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Expiration
A. Largely a passive process which depends
on natural lung elasticity
B. As muscles relax, air is pushed out of the
lungs
C. Forced expiration can occur mostly by
contracting internal intercostal muscles to
depress the rib cage
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Expiration
Figure 13.7b
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Pressure Differences in the Thoracic
Cavity
A. Normal pressure within the pleural space
is always negative (intrapleural pressure)
B. Differences in lung and pleural space
pressures keep lungs from collapsing
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Nonrespiratory Air Movements
A. Can be caused by reflexes or voluntary
actions
B. Examples:
Cough and sneeze – clears lungs of debris
Laughing
Crying
Yawn
Hiccup
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Respiratory Volumes and Capacities
A. Normal breathing moves about 500 ml of air with
each breath (tidal volume [TV])
B. Many factors that affect respiratory capacity
1. A person’s size
2. Sex
3. Age
4. Physical condition
C. Residual volume of air – after exhalation, about
1200 ml of air remains in the lungs
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Respiratory Volumes and Capacities
D. Inspiratory reserve volume (IRV)
Amount of air that can be taken in forcibly
over the tidal volume
Usually between 2100 and 3200 ml
E. Expiratory reserve volume (ERV)
Amount of air that can be forcibly exhaled
Approximately 1200 ml
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Respiratory Volumes and Capacities
F. Vital capacity
The total amount of exchangeable air
Vital capacity = TV + IRV + ERV
G. Dead space volume
Air that remains in conducting zone and
never reaches alveoli
About 150 ml
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Respiratory Volumes and Capacities
H. Functional volume
Air that actually reaches the respiratory
zone
Usually about 350 ml
I. Respiratory capacities are measured with a
spirometer
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Respiratory Capacities
Figure 13.9
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