Transcript The Respiratory System

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Provides extensive gas exchange surface
area (alveoli) between air and blood
Moves air to and from alveoli
Protects respiratory surfaces from outside
environment
Produces sounds
Participates in olfactory sense (smell)
The organs of the respiratory
system are the nose,
pharynx, larynx, trachea,
bronchi and the smaller
branches, and the lungs and
the alveoli.
Branch
from the
pulmonary
vein
(oxygen-rich
blood)
Branch
from the
pulmonary
artery
(oxygen-poor
blood)
Terminal
bronchiole
Nasal
cavity
Pharynx
Left
lung
Alveol
50 µm
Larynx
Esophagus
Trachea
50 µm
Right lung
Bronchus
Bronchiole
Diaphragm
Heart
SEM
Colorized SEM
 Conducting Passageways
 Consists of the nose and pharynx
Figure 23–3
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Air enters the nasal cavity through the
nostrils.
Nasal hairs prevent the entry of large
particles carried in the air.
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Nasal cavity is a hollow space behind the
nose.
The nasal septum divides it into left and right
sides.
Superior portion of nasal cavity is the
olfactory region
• Lines the nasal cavity
• Rests on a rich
network of thin-walled
blood vessels that
warm and humidify
the air as it flows
• Breathing through
mouth bypasses this
important step
create a gentle current that
moves contaminated mucus
toward the pharynx, where it
is swallowed and digested by
stomach juices.
When external temp is
extremely cold, these cilia
become sluggish, allowing
mucus to dribble out nostrils.
The nasal cavity is surrounded by a ring
of paranasal sinuses, which are air filled
spaces in skull
Reduce weight of skull
Resonating chambers that affect
speech
The tear ducts also empty into the
nasal cavities
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Located in the frontal, sphenoid, ethmoid, and
maximally bones.
A chamber shared by
digestive and
respiratory systems
 Both food and air share
the passageway
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Superior portion of
the pharynx
Contains
pharyngeal tonsils
(adenoids) and
openings to left
and right auditory
tubes
Middle portion of the
pharynx
 Communicates with
oral cavity
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Inferior portion of the
pharynx
 Extends from hyoid
bone to entrance to
larynx and esophagus
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Contagious VIRAL respiratory infection
Indirect causes: chilling, fatigue, lack of
proper food, and not enough slepp
Handwashing is the best preventative
measure
Sometimes called an upper respiratory
infection
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Red, inflammed throat
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Inflammation of the larynx of voice box
Often secondary to other respiratory
infections
Symptoms: Sore throat, loss of voice,
dysphagia (difficulty swallowing)
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Infection of the mucusou membrane that
lines sinus cavities
Can be caused by bacteria or virus
Symptoms: headache or pressure, thick
nasal discharge, loss of voice resonance
(sounds different)
 Consists of the larynx, trachea, bronchi,
and the lungs
 The lungs consist of bronchioles and
alveoli
Figure 23–4
▪ Routes air and food into the proper
channels
▪ Plays a role in speech
▪ vocal cords: vibrate with expelled air
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3 large, unpaired
cartilages form the
larynx:
 the epiglottis
 the thyroid cartilage
 the cricoid cartilage
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Ligaments attach to
thyroid cartilage and
hyoid bone
guardian of the
airways
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Also called the
Adam’s apple
Support and protect
the glottis, the
entrance to the
trachea
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Form lower portion of
larynx
Support and protect
the glottis, the
entrance to the
trachea
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Prevents entry of food and liquids into
respiratory tract
During swallowing:
 the larynx is elevated
 the epiglottis folds back over glottis
 When we are not swallowing, the epiglottis
does not restrict the passage of air into the
lower respiratory passages.
When we
swallow food or
fluids, the larynx
is pulled upward
and the epiglottis
tips forming a lid
over the opening
of the larynx
This routes
food into the
esophagus
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Air passing through glottis vibrates vocal
folds and produces sound waves
Sound is varied
• Changing the shapes of the pharynx and oral
cavity and using the tongue and lips to
transform the sound waves into words
• Contracting and relaxing muscles alter the
tension on the vocal cords to control the pitch.
During normal
breathing, the
vocal cords are
relaxed and the
opening between
them, the glottis,
is a triangular slit
When food or liquid is
swallowed, muscles
within the false vocal
cords close the glottis,
which also helps to
prevent food or liquid
from entering the
trachea.
Figure 23–5
Figure 23–6
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Common Term:
windpipe
Located anterior to
the esophagus and
into the thoracic
cavity, where it splits
into right and left
bronchi
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15–20 tracheal cartilages:
 strengthen and protect airway
 discontinuous where trachea contacts esophagus
▪ open parts of the rings allow the esophagus to expand
when we swallow a large piece of food.
▪ solid portion support the trachea walls and keep it open
in spite of the pressure changes that occur during
breathing.
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Lined with lined with ciliated
mucosa
 beat continuously and in a
direction opposite to that of
incoming air.
 propel mucus, loaded with dust
and other debris, away from lungs
to the throat, where it can be
swallowed or spat out.
Smoking inhibits ciliary activity and
ultimately destroys the cilia.
Without these cilia, coughing is the
only means of preventing mucus
from accumulating in the lungs.
 Since the trachea is the only way that air can
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enter the lungs, tracheal obstruction is lifethreatening
Heimlich maneuver: procedure in which the air
in a person’s own lungs in used to pop out an
obstruction piece of food.
In emergency situations, a tracheotomy is done
to provide an alternate route for air to reach the
lungs
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Temporary surgical
procedure which
involves making an
opening so that air can
bypass a structure in
the trachea.
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Branched airways leading from the trachea to
the microscopic air sacs in the lungs.
① Primary bronchi (left and right)
② Secondary bronchi
③ Tertiary bronchi
④ Bronchioles
⑤ Aleveolar ducts
⑥ Alveolar sacs
⑦ Alveoli
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Inflammation of
the mucous
membrane of the
trachea and
bronchiole tubes,
producing excess
mucous
Causes
constriction and
breathing difficulty
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Provides a large surface area of thin simple
squamous epithelial cells through which
gases can be easily exchange
In both lungs,
 ~300 mil alveoli
 ½ size of tennis court
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Oxygen diffuses from the alveoli into the
blood in nearby capillaries
Carbon dioxide diffuses from the blood into
the alveoli
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Lungs are soft and
spongy and coneshaped
Base of lung rests on
the diaphragm
Each lung enclosed in
a pleural cavity
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3 lobes
 superior, middle,
& inferior
 separated by
horizontal and
oblique fissures
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Displaced upward
by liver
Wider than left
lung
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2 lobes
 superior and inferior
 separated by an
oblique fissure
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Longer than right
lung
Displaced leftward
by the heart
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Pneumonia is an inflammation of the lungs caused
by an infection. Alveoli fill with exudates (thick fluid)
Many different organisms can cause it, including
bacteria, viruses, and fungi.
Pneumonia is a common illness that affects millions
of people each year in the United States.
Symptoms – chest pain, fever, chills, dyspnea
(difficult, labored, painful breathing)
The symptoms of pneumonia range from very mild
to very severe, even fatal.
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Inflammatory airway obstruction
Caused by allergen or psychological stress
5% of Americans have asthma
Symptoms: difficulty exhaling, dyspnea,
wheezing, tightness in chest
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Contagious bacterial infection that involves the lungs,
but may spread to other organs. It causes
inflammation, the formation of tubercules within tissue,
and even tissue death.
Caused by the bacteria Mycobacterium tuberculosis
You can get TB by breathing in air droplets from a cough
or sneeze of an infected person.
Symptoms: cough, low grade fever in the afternoon,
weight loss and night sweats
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Alveoli become over-dilated, lose their
elasticity, can’t rebound, may even
eventually rupture
Air becomes trapped, can’t exhale- forced
exhalation required
Reduced exchange of O2 and CO2
Dyspnea increases as disease progresses
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Found mainly in smokers
Symptoms: chronic cough and weight loss
Diagnosis: x-ray and bronchoscopy (flexible
tube passed through mouth or nose into
bronchi and lungs
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Blood clot breaks off and travels to the lung
Occurs after surgery or when a person has
been on bed rest
Symptoms: sudden severe chest pain,
dyspnea
 Consists of 2 layers
 Parietal pleura: lines the walls of the thoracic cavity
 Visceral pleura: lines the surface of each lung
 No significant space exists between the visceral and
parietal pleura, but the potential space between
them is what is referred to as the pleural cavity.
 Pleural fluid lubricates the space between the two
layers reducing friction as they move against one
another during breathing
Notice the relationship between the heart and lungs
Notice the pleura and pleural cavities
Figure 23–8
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Inflammation of the lining of the lungs and
chest (the pleura) that leads to chest pain
(usually sharp) when you take a breath or
cough.
May develop when you have lung
inflammation due to infections such as
pneumonia or tuberculosis.
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Ventilation (breathing), the movement of air in and out of
the lungs, is composed of inspiration and expiration.
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Atmospheric pressure is the force that moves air into the
lungs.
When pressure on the inside of the lungs decreases, higher
pressure air flows in from the outside.
Air pressure inside the lungs is decreased by increasing the
size of the thoracic cavity; due to surface tension between
the two layers of pleura, the lungs follow with the chest
wall and expand.
Muscles involved in expanding the thoracic cavity include
the diaphragm and the external intercostal muscles.
As the lungs expand in size, surfactant keeps the alveoli
from sticking to each other so they do not collapse when
internal air pressure is low.
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The forces of expiration are due to the elastic
recoil of lung and muscle tissues and from the
surface tension within the alveoli.
Passive process
Forced expiration is aided by thoracic and
abdominal wall muscles that compress the
abdomen against the diaphragm.
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The measurement of different air volumes is
called spirometry, and it describes four distinct
respiratory volumes : tidal volume, inspiratory
reserve volume, expiratory reserve volume and
the residual volume
One inspiration followed by expiration is called a
respiratory cycle
Normal adult: 14-20 respirations per minute
 Increases with exercise, body temperature, disease
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The amount of air that enters or leaves the
lungs during one respiratory cycle is the tidal
volume.
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During forced inspiration,
an additional volume, the
inspiratory reserve
volume, can be inhaled
into the lungs.
IRV + TV gives us the
inspiratory capacity.
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During a maximal forced
expiration, an expiratory
reserve volume can be
exhaled, but there
remains a residual
volume in the lungs.
Adding the two together
gives us the functional
reserve capacity.
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Vital capacity is the tidal volume plus
inspiratory reserve and expiratory reserve
volumes combined.
Vital capacity plus residual volume is the total
lung capacity.
Anatomic dead space is air remaining in the
bronchial tree.
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Normal breathing is a rhythmic, involuntary act
even though the muscles are under voluntary
control.
Breathing controlled by two factors: Neural
factors and Chemical factors
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Groups of neurons in the
brain stem (the medulla
oblongata and the pons)
comprise the respiratory
center, which controls
breathing by causing
inspiration and expiration
and by adjusting the rate
and depth of breathing.
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Chemicals, lung tissue stretching, and emotional
state affect breathing.
Chemosensitive areas (central chemoreceptors)
are associated with the respiratory center and are
sensitive to changes in the blood concentration of
carbon dioxide and hydrogen ions.
 If either carbon dioxide or hydrogen ion concentrations
rise, the central chemoreceptors signal the respiratory
center, and breathing rate increases.
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Peripheral chemoreceptors in the carotid sinuses
and aortic arch (heart) sense changes in blood
oxygen concentration, transmit impulses to the
respiratory center, and breathing rate and tidal
volume increase.
An inflation reflex, triggered by stretch receptors in
the visceral pleura, bronchioles, and alveoli, helps
to prevent overinflation of the lungs during forceful
breathing.
Hyperventilation lowers the amount of carbon
dioxide in the blood.
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The alveoli are the only sites of gas exchange
between the atmosphere and the blood.
The alveoli are tiny sacs clustered at the distal
ends of the alveolar ducts.
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The respiratory membrane consists of the
epithelial cells of the alveolus, the endothelial
cells of the capillary, and the two fused
basement membranes of these layers.
Gas exchange occurs across this respiratory
membrane.
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Gases diffuse from areas of higher pressure
to areas of lower pressure.
In a mixture of gases, each gas accounts for a
portion of the total pressure; the amount of
pressure each gas exerts is equal to its partial
pressure.
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When the partial pressure of oxygen is higher in
the alveolar air than it is in the capillary blood,
oxygen will diffuse into the blood.
When the partial pressure of carbon dioxide is
greater in the blood than in the alveolar air, carbon
dioxide will diffuse out of the blood and into the
alveolus.
A number of factors favor increased diffusion; more
surface area, shorter distance, greater solubility of
gases, and a steeper partial pressure gradient
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Gases are transported in association with
molecules in the blood or dissolved in the plasma.
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Over 98% of oxygen is carried in the blood bound
to hemoglobin of red blood cells, producing
oxyhemoglobin.
Oxyhemoglobin is unstable in areas where the
concentration of oxygen is low, and gives up its
oxygen molecules in those areas.
More oxygen is released as the blood concentration
of carbon dioxide increases, as the blood becomes
more acidic, and as blood temperature increases.
A deficiency of oxygen reaching the tissues is called
hypoxia and has a variety of causes.
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Carbon dioxide may be transported dissolved in
blood plasma, as carbaminohemoglobin, or as
bicarbonate ions.
Most carbon dioxide is transported in the form of
bicarbonate.
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