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The Respiratory
System:
Study Guide
Anatomy
Respiratory system consists of:
Nose
Pharynx (throat)
Larynx (voice box)
__________ (windpipe)
Bronchi
Lungs
Can be divided:
Structurally
_____________
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Structural Components
Upper respiratory system
Nose
____________
Associated structures
Lower respiratory system
Larynx
Trachea
Bronchi
______________
Functional Components
Conducting zone
Nose
Nasal cavity
_____________
Larynx
Trachea
Bronchi
_____________
Terminal bronchioles
Respiratory zone
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
_______________
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The Nose
External nose
External nares/nostrils
Bony framework
Frontal bone
_________ bones
Maxillae
Cartilaginous framework
Septal cartilage
Lateral nasal cartilages
_________ cartilages
Nose:
Internal nasal cavity
Nasal cavity
Internal nares
Paranasal sinuses
Nasolacrimal
ducts
__________ septum
Superior, middle,
inferior meatuses
_______________
epithelium
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Pharynx (throat)—3 divisions
1. Nasopharynx
2. _______________
3. Laryngopharynx
Lower Respiratory System:
Larynx (voicebox)
Connects laryngopharynx
with ____________.
Composed of
cartilaginous walls held
in position by ligaments
and skeletal muscles
___________cells: produce
mucus to help trap dust
Epiglottis
Glottis
Thyroid cartilage
Cricoid cartilage
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Swallowing
Pharynx and larynx are elevated
___________ causes the pharynx to widen to receive food/drink
Elevation of larynx causes epiglottis to move down and close
the glottis
Keeps food/drink in the esophagus ONLY
If something slips by and into larynx à ___________ reflex
Voice Production
Mucus membrane of larynx
forms two pairs of folds
1. Ventricular folds
(________ vocal cords)
No function in voice
production
Can hold breath against
pressure in thoracic cavity
E.g. lifting heavy object
2. ____________ folds (true
vocal cords)
Sound production
Complex relationship
between ligaments,
muscles, cartilage, and air
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Vocal cords + air =
How sound is produced
1. Bands of ___________ligaments are stretched between
pieces of rigid cartilages
2. Laryngeal muscles attach to rigid cartilage and vocal
folds
3. ___________ contract, cartilages move, elastic ligaments
pulled tight, vocal cords stretched out, glottis narrows
4. Air passing through vibrates folds and produces sound
(phonation)
Pitch variation is related to vocal fold tension
Greater air pressure results in how loud sounds are
produced
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Physical Mechanics of Speech
Sound originates at _______________ of vocal cords
Pharynx, mouth, nasal cavity, and paranasal sinuses all
involved
How sound resonates gives it a human and individual quality
Muscles of face, tongue, and lips help us ____________ words
Shape of oral cavity is important, too
Vowel sounds
Contracting and relaxing muscles in pharynx
Whisper
Closing all but posterior portion of glottis; vocal folds do not
vibrate
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Trachea
Aka windpipe, about 5”
in length
Stacked horizontal rings
of hyaline cartilage,
shaped like the letter ‘C’
Opening of each ‘C’
faces the esophagus
Trachealis
Allows ___________ of
trachea to subtly change
during breathing
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Primary bronchi
branch from trachea Bronchi
into lungs
Incomplete rings of
cartilage
Lined with
pseudostratified
columnar
_________________
Right primary
bronchus
More vertical,
shorter than left
Left primary
bronchus
___________
Projection of last
tracheal cartilage
Sensitive coughing
reflex
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Bronchial Tree
Secondary (lobar) bronchi
Tertiary (segmental) bronchi
Bronchioles
Terminal bronchioles
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The Lungs
Paired, spongy,
cone-shaped organs
Having two
separated organs is
a good thing
Protective coverings
__________ pleura
Visceral pleura
Pleural cavity
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Base
Lung Anatomy
Apex
Hilum
Cardiac notch
_____ lung is
about 10%
smaller than right
Right lung
Thicker, broader,
but shorter to
accommodate
position of
_________
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Each lobule: Lobules
Has a lymphatic vessel
Arteriole
Venule
Branch from terminal
bronchiole
Respiratory bronchioles
Alveolar budding from
walls
First part of respiratory
____________
Turn into alveoli _______
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Alveolar sac Alveoli
Contain multiple alveoli connected to
common alveolar duct
Arteriole and venule have a network of
capillaries for gas exchange
2 types of alveoli epithelium cells
within the walls:
Type I _____________ cells
Main sites of gas exchange
More numerous
Type II alveolar cells (septal cells)
Fewer in number
Between Type I cells
Secrete ___________________
Surfactant
Helps alveoli stay inflated by reducing
surface tension (more later)
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Respiratory Membrane:
4 layers:
Getting O2 in and CO2 out
1. Type I and Type II
alveolar cell wall
2. Epithelial basement
membrane
Underlying alveolar
wall
3. ____________________
_______________
4. Capillary
endothelium
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3 steps: Respiration
1. Pulmonary ventilation (breathing)
Inhalation (aka inspiration) and exhalation (aka expiration)
Air exchange between the atmosphere and the alveoli of
the lungs
2. External respiration
Pulmonary exchange of gases across respiratory
membrane between alveoli of the lungs and the blood in
pulmonary capillaries
Pulmonary capillary blood gains ______ and loses CO2
3. Internal respiration
Tissue exchange of gases between blood in systemic
capillaries and tissue cells
Blood loses O2 and gains ___________
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Pulmonary Ventilation:
Pressure Changes
Air moves into lungs when air pressure inside lungs
is less than air pressure in the atmosphere outside
the body
Air moves out of lungs when air pressure inside the
lungs is __________ than air pressure outside the body
Inhalation (inspiration)
Lungs must expand
Lung volume is increased
Pressure is decreased below atmospheric pressure
Air flows into lungs
Boyle’s law
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Boyle’s Law
The volume of a gas varies inversely with its
pressure
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How lungs expand during
inhalation:
Muscle contractions key:
Diaphragm contracts
Becomes flatter, ______________
Increases size of thoracic cavity
Responsible for ~ 75% of air that enters the lungs
Can be confined due to advanced pregnancy,
excessive obesity, or confining abdominal clothing
External intercostals contract
Pull ribs upward and _____________
Increases size of thoracic cavity
Responsible for ~ 25% of air that enters the lungs
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Intrapleural Pressure:
Essential to keeping alveoli
from collapse
Intrapleural pressure
At rest, is slightly _____________ than
atmospheric pressure
During diaphragm and external intercostal
contractions, the volume of the pleural cavity
increases
Drops pressure
Creates a ‘suction’ that helps prevent alveoli
from collapsing like a balloon, preventing
collapsed lung
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Alveolar Pressure:
Volume in Getting air into alveoli
lungs increase,
pressure inside
lungs (alveolar
pressure) drops
slightly
Alveolar
pressure is
now lower
than
atmospheric
Air flows from
high to lower
pressure à air
goes ____ lungs
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Elastic recoil Exhalation
Muscles relax
Thoracic wall
and lungs
spring back into
place after
being stretched
Pressure
increases inside
alveoli until
slightly greater
that atmospheric
à air moves
_________
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All Together
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Other factors impacting
pulmonary ventilation
1. Surface tension of alveolar fluid
Respiratory distress syndrome
2. Compliance of the lungs
High compliance = easy
Low compliance = difficult
Elasticity
Surface tension
3. Airway resistance
How _______ air can flow through airways
Narrowing/obstruction = resistance
COPD, asthma
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Rate of Pulmonary and
Systemic Gas Exchange
External respiration
Exchange between ____________ and capillaries
Deoxygenated blood to oxygenated blood
Internal respiration
Exchange between _____________ and tissue cells
Oxygenated blood to deoxygenated blood
Other factors:
Partial pressure difference of the gases
Surface area available for gas exchange
Diffusion distance
Molecular weight and solubility of the gases
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External vs Internal
Respiration
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Arteries and Vein Arrangement:
Pulmonary vs Bronchial Circulation
Pulmonary Circulation
Blood circulates between ___________ and lungs ONLY
Veins and arteries are ______________
Arteries carry deoxygenated blood to capillaries, venules
carry oxygenated blood to pulmonary veins
100% of total blood circulates through here
Bronchial Circulation
Part of _____________ circulation
Veins and arteries are ‘normal’ here
Arteries carry oxygenated blood, veins carry deoxygenated
Supplies oxygenated blood to parts of the lungs themselves
Originates from aorta
Only 1-3% of blood circulates through here
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Relationship between Hemoglobin and
Oxygen Partial Pressure
Oxyhemoglobin (Hb-O2)
Oxygen bound to ___________________
Fully saturated
Every __________ atom has a molecule of oxygen
Partially saturated
Combo of hemoglobin and Hb-O2
Percent saturation of hemoglobin
Average saturation of hemoglobin with oxygen
Example: if each hemoglobin is bound to 2 oxygen, it is 50% saturated
Affinity
How tightly hemoglobin ____________
Factors that impact affinity
Acidity
Partial Pressure of Carbon Dioxide
Temperature
BPG (2,3-biphosphoglycerate)
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Carbon Dioxide Transport
1. Dissolved CO2
~7-10% in blood plasma
2. Bound to hemoglobin
Carbaminohemoglobin (Hb-CO2)
~20-23% of CO2
3. Bicarbonate ions
~70% of CO2
CO2 reacts with H20 à HCO3-
Chloride shift
HCO3- moves ___________ of the cell, Cl- moves ________
Keeps electrical balance between blood plasma and RBC
cytosol
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Oxygen
and
Carbon
Dioxide
Transport
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Respiratory system control
Respiratory center
Clusters of neurons within medulla oblongata and pons of brain stem
Medullary respiratory center
In ______________. ________________
Controls basic rhythm of respiration
Two areas:
1. Dorsal respiratory group
Establish basic rhythm of breathing
Quiet breathing—occurs at rest, no cognitive thought needed.
Forced breathing—active manipulation of breathing. Requires more
muscles.
Generates impulses for about 2 seconds -->muscles of respiratory
system contract, inhalation
2. Ventral respiratory group
_____________ during forceful breathing
Impulses cause forceful exhalation
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Other factors influencing respiration
Chemoreceptors
Responsive to changes in _____________ and __________________
Provide input to respiratory center
Proprioceptors
Monitor movements in muscles and joints
Feeds back info to respiratory center
Stretch receptors
In walls of bronchioles and bronchi
Helps prevent _________________ of lungs
Other factors:
Body temperature—increases breathing when high, drops when low
Temporary apnea—what happens when you unknowingly step into a
freezing shower!
Pain—duration increases or decreases respiration rate
BP changes—can adjust breathing in response to BP
Stimulation of limbic system—anticipation of activity
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