Download Respiratory System

Respiratory System
Courtney Shelton CST, BA
ST
Objectives
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Identify respiratory tracts
Identify structures of respiration
Discuss respiration and mechanics of
breathing
Discuss the exchange of gases
Discuss volumes
Discuss neurological control
Overview
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The organs of the respiratory system perform
two basic funtions
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Air distribution
Gas exchange
Overview
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In addition to air distribution and gas
exchange, the respiratory system:
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Filters air
Warms air
Humidifies air
Overview
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Respiratory organs (or organs associated with
the respiratory system such as the sinuses)
also influence speech production and make
olfaction possible.
Structural Plan
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Organs
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Nose
Pharynx
Larynx
Trachea
Bronchi
lungs
Structural Plan
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The basic design is that of a tube with many
braches ending in millions of extremely tiny,
very thin-waled sacs called alveoli.
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Air distribution system is like an upside down
tree.
Structural Plan
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Alveoli function to exchange gases by
distributing the air close enough to blood for
the gas exchange to occur.
The alveoli can do this because of 2
characteristics.
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The wall of each alveolus is made of a single
layer of cells. The thin barrier is called the
respiratory membrane.
There are millions of alveoli.
Respiratory Tracts
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Divided into upper and lower.
Upper respiratory tract includes:
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Nose
Pharynx
Larynx
Lower respiratory tract includes:
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Trachea
Bronchial tree
Lungs
Respiratory Mucosa
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Defined as the membrane that lines most of
the air distribution tubes in the system.
WARNING! Don’t confuse this with the
respiratory membrane! It separates the air in
the alveoli from the blood in surrounding
capillaries.
Respiratory Mucosa
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The layer of protective mucus that covers a
large portion of the membrane that lines the
respiratory tree serves as the most important
air purification mechanism.
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It forms a mucus blanket.
Cilia
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Cilia move mucus from the lower portions of
the bronchial tree upward toward the pharynx.
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Cilia only beat in one direction.
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Cigarette smoke paralyzes cilia causing an
accumulation of mucus resulting in a
smoker’s cough.
Nose
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Air enters through the external nares or
nostrils.
It flows into left and right nasal cavities,
which are lined with respiratory mucosa.
Nasal septum separates the two cavities.
Four paranasal sinuses drain into the nasal
cavities. They are: frontal, maxillary,
sphenoidal, and ethmoidal.
Nose
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The paranasal sinuses are lined with a mucous
membrane that assists in the production of
mucus for the resp tract.
They also lighten the skull and serve as
resonant chambers for the production of
sound.
Pharynx
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Most people call this the throat!
It is divided into three portions
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Nasopharynx- uppermost
Oropharynx- behind mouth
Laryngopharynx- lowest segment
Pharynx
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Air and food pass through this structure.
The left and right auditory tubes open into the
nasopharynx. They connect the inner ear with
the nasopharynx.
The connection permits equalization of air
pressure between the middle and inner ear.
Pharynx
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Pharyngeal tonsils are located in the
nasopharynx.
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Palatine tonsils are located in the oropharynx.
Larynx
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Voice box
Composed of several layers of cartilage. The
largest is the thyroid cartilage (Adam’s apple).
Two short fibrous bands, the vocal cords,
stretch across the interior of the larynx. When
they are tense, the voice is high pitched.
Larynx
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Glottis- the space between the vocal cords.
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Epiglottis- cartilage that partially covers the
opening of the larynx. Acts like a trap door
that closes during swallowing to prevent food
from entering the trachea.
Trachea
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Windpipe
Extends from larynx to the bronchi
Functions as a passageway for air
C-shaped rings with soft tissue in between
them
Bronchi, Bronchioles, Alveoli
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Trachea is the main trunk of the chair
Primary bronchi are the right and left
bronchus. They are the first branches off the
trachea.
In each lung, they branch into smaller or
secondary bronchi whose walls are kept open
by rings of cartilage.
Bronchi, Bronchioles, Alveoli
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The secondary bronchi divide into smaller and
smaller tubes. Ultimately, these tubes branch into
tiny tubes whose walls only have smooth muscle.
These tiny tubes are bronchioles.
The bronchioles subdivide into microscopic tubes
called alveolar ducts which resemble the main stem
of grapes.
Each alveolar duct ends in several alveolar sacs,
which look like a bundle of grapes. Each grape is an
alveoli.
Alveoli
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Effective in gas exchange
Extremely thin walled
Lie in contact with capillaries
Millions in each lung
Surface of the respiratory membrane inside the
alveolus is covered by surfactant that reduces surface
tension in the alveoli and keep them from collapsing
as air moves in and out
Lungs and Pleura
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Lungs
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Right has 3 lobes
Left has 2 lobe
Apex is the narrow, superior portion under the
collarbone
Base rests on the diaphragm
Lungs and Pleura
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Pleura
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Covers outer surface of the lungs and lines the inner
surface of the rib cage
Extensive, thin, moist, and slippery membrane
Parietal and visceral
Intrapleural space lies between the 2 pleural membranes
and contains fluid
Pneumothorax: presence of air in the intrapleural space
on one side of the chest. Additional air increases pressure
on the lung causing it to collapse.
Respiration
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Exchange of gases between a living organism and its
environment
Breathing aka pulmonary ventilation is the process
that moves air into and out of the lungs
The exchange of gases between air in the lungs and
in the blood is called external respiration
Exchange of gases between the blood and the cells is
called internal respiration
Mechanics of Breathing
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2 phases
Inspiration- inhalation, moves air into lungs
Expiration- exhalation, air moves out of lungs
Air moves from an area where pressure is high to an
area where pressure is lower.
Respiratory muscles are responsible for the changes
in the shape of the thoracic cavity that cause the air
movements involved in breathing.
Inspiration
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Occurs when chest cavity enlarges
As cavity enlarges, the lungs expand and air
rushes in
Muscles of respiration are called inspiratory
muscles and include the diaphragm and the
external intercostals
Expiration
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Inspiratory muscles relax
Expiratory muscles are internal intercostals
and abdominal muscles
As the thoracic cavity decreases in size, the
air pressure within it increases and air flows
out of the lungs
Exchange of Gases in Lungs
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Diffusion is movement down a concentration
gradient
Oxygen is continually removed from the
blood and used by body cells
Alveolar air is rich in oxygen: diffusion
causes movement of oxygen from the area of
high concentration (alveolar air) to the area of
low concentration (capillary blood)
Exchange of Gases in Lungs
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Blood flowing through the lung capillaries is
high in carbon dioxide
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As cells remove oxygen, they add the waste
product carbon dioxide to the blood
Exchange of Gases in Tissues
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Internal respiration- exchange of gases that occurs
between blood in tissue capillaries and the body cells
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Movement of oxygen and carbon dioxide during
internal respiration is opposite from external
respiration
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Diffusion is responsible for this movement
Volumes of Air Exchanged in
Pulmonary Ventilation
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Spirometer- a device that measures the
amount of air exchanged in breathing.
We breathe in about a pint of air with each
breath.
This amount is the tidal volume.
Vital capacity is the largest amount of air that
we can breathe out in one expiration.
Volumes, cont’d
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Expiratory reserve volume is the amount of air that
can be forcibly exhaled after expiring the tidal
volume.
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Inspiratory reserve volume is the amount of air that
can be forcibly inspired over and above a normal
respiration.
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Residual volume is the air that remains in the lungs
after the most forceful expiration.
Regulation of Respiration
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The more work the body does, the more
oxygen must be delivered to the cells.
One way to do this is to increase the rate and
depth of respirations.
Heart beats faster, breathe faster, tidal volume
increases during exercise.
Regulation of Respiration
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Normal respiration depends on proper
functioning of the muscles of respiration.
They are stimulated by nervous impulses from
the respiratory control centers located in the
medulla and pons.
These receptors sense the need for changing
the rate or depth of respirations.
Regulation of Respiration
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The 2 most important control centers are in
the medulla
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Inspiratory center
Expiratory center
Pons has a modifying function
Cerebral Cortex
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Influences respiration by modifying the rate at which
neurons “fire” in the inspiratory and expiratory
centers.
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We can voluntarily control our breathing, but there
are limitations.
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Regardless of cerebral intent to the contrary, we
resume breathing when our bodies sense the need for
more oxygen.
Receptors Influencing Respiration
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Chemoreceptors:
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Located in the carotid and aortic bodies
Sensitive to increases in blood carbon dioxide
levels and decreases in blood oxygen levels
Receptors Influencing Respiration
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Pulmonary Stretch Receptors:
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Located throughout the pulmonary airways and in
the alveoli
Protect the resp system from excess stretching
caused by harmful overinflation
Types of Breathing
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Eupnea- normal respiratory rate
Hyperventilation- very rapid and deep respirations
Hypoventilation- very slow and shallow respirations
Dyspnea- labored or difficult breathing
Apnea- breathing stops completely for a short
period
Respiratory arrest- failure to resume breathing after
a prolonged period of apnea