Transcript THE RESPIRATORY SYSTEM

THE RESPIRATORY SYSTEM
FUNCTIONS OF THE RESPIRATORY
SYSTEM
Transports air into the lungs and facilitates the
diffusion of oxygen into the blood stream
 Receives carbon dioxide from the blood and
exhales it
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Organs of the Respiratory system
 Nose
 Pharynx
 Larynx
 Trachea
 Bronchi
 Lungs alveoli
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 13.1
SLIDE 13.1
ORGANIZATION OF THE RESPIRATORY
SYSTEM
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Upper Respiratory System – Nose, nasal cavity,
paranasal sinuses, and pharynx
Lower Respiratory System – Larynx, Trachea,
Bronchi, Bronchioles, Alveoli
NOSE, NASAL CAVITY, PARANASAL SINUSES
Nose - Primary passageway for air entering the
respiratory system
 Nose is the only externally visible part of the
respiratory system
 The maxillary, nasal, frontal, ethmoid, and
sphenoid bones form the lateral and superior
walls of the nasal cavity
 The mucous secretions produced in the paranasal
sinuses keep the nasal cavity moist and clean
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PHARYNX (THROAT)
Chamber shared by the digestive and respiratory
systems
 The pharnyx is divided into the nasopharynx,
oropharynx, and laryngopharynx
1. Nasopharynx – superior portion of pharynx
2. Oropharynx – oris/mouth; extends between the
soft palate and the base of the tongue at the
level of the hyoid bone
3. Laryngopharynx – inferior part of pharynx;
entrance to larynx and esophagus
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LARYNX (VOICEBOX)
Cartilaginous structure that surrounds and
protects the glottis (narrow opening where
inhaled air leaves the pharynx and enters larynx)
 Epiglottis – superior to the glottis; composed of
elastic cartilage; during swallowing the larynx is
elevated and the epiglottis folds back over the
glottis, preventing the entry of both liquids and
food into the respiratory tract
 Sound production - air passing through the
glottis vibrates the vocal folds and produces
sound waves (phonation)
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TRACHEA (WINDPIPE)
Tough, flexible tube
 Transports air between the larynx and primary
bronchi
 Cilia and mucus protect the respiratory tree by
trapping inhaled debris and sweeping it toward
the pharynx, where it is removed through
coughing or swallowing
 Branches within the mediastinum, giving rise to
the right and left primary bronchi
 Right bronchus (most likely site for a lodged
object) supplies the right lung, left bronchus
supplies the left lung
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LUNGS
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Soft, spongy, cone shaped organs in the thoracic
cavity
Separated medially by the heart and the
mediastinum; enclosed by the diaphragm and the
thoracic cage
Air moves into the lungs through the trachea
(windpipe)
The trachea branches out into two bronchi (main
airways that reach into each lung)
Bronchioles (network of tubes) – small passageways
that lead to the alveoli
At the end of each bronchiole are groups of
microscopic structures called alveoli (thin-walled air
sacs covered with capillaries)
BREATHING – VENTILATION
Movement of air from
outside the body into
the bronchial trees and
alveoli
 Inspiration – inhalation
 Expiration – exhalation
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MECHANICS OF BREATHING
Inspiration (inhalation):
 The size of the thoracic cavity increases
when the diaphragm moves downward
 As the volume within the lungs increases,
the gases within the lungs spread out
 This results in a decrease of gas pressure
and produces a partial vacuum (pressure
less than atmospheric pressure) which
pulls air in through the nose or mouth
 Air continues to move into the lungs until
it equals atmospheric pressure
MECHANICS OF BREATHING
Expiration (exhalation):
 When we breathe out, the diaphragm
moves upward, forcing the chest cavity to
get smaller
 As volume decreases, the gases inside the
lungs are forced more closely together,
and the pressure rises to a point higher
than atmospheric pressure
 This causes the gases to flow out of the
nose and mouth to equalize the pressure
inside and outside the lungs
RESPIRATION
With each inhalation, air fills a large portion of
the millions of alveoli (air sacs)
 Diffusion – oxygen moves from the alveoli to the
blood through the capillaries lining the alveolar
walls
 Once oxygen is in the bloodstream it gets picked
up by the hemoglobin in red blood cells
 This oxygen rich blood flows back to the heart,
which pumps it through the arteries to your body
 Carbon dioxide moves out of the cells into the
capillaries and blood rich in carbon dioxide
returns to the heart via the veins
 From the heart, this blood is pumped to the
lungs, where carbon dioxide passes into the
alveoli to be exhaled
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LUNGS AND RESPIRATORY PROBLEMS
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Asthma – chronic inflammatory lung disease that
causes airways to tighten and narrow
Emphysema – lungs produce an excessive
amount of mucus and the alveoli become
damaged (caused by long-term smoking)
Bronchitis – membranes lining the bronchial
tubes become inflamed and an excessive amount
of mucus is produced; a bad cough develops to get
rid of the mucus
RESPIRATORY SYSTEM DISORDERS/DISEASES
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Cystic fibrosis - most common lethal inherited
disease; respiratory mucus is extremely dense and
cannot be transported by the respiratory defense
system which leads to frequent bacterial infections
(average predicted age of survival = 37 years)
Atelectasis – complete or partial collapse of a lung or
lobe of a lung; develops when the alveoli within the
lung become deflated; caused by a blockage of the air
passages, by pressure on the outside of the lung
(injury), lung tumor, inhaled object
Apnea – temporary absence or cessation of breathing;
can cause decreased oxygen levels in the body (infant
apnea and sleep apnea)
RESPIRATION
Pulmonary ventilation – air must move into and
out of the lungs so that the gases in the alveoli are
refreshed
 External respiration – gas exchange (oxygen
loading and carbon dioxide unloading) between the
blood and alveoli
 Respiratory gas transport – oxygen and carbon
dioxide must be transported to and from the lungs
and cells of the body via the blood
 Internal respiration – gas exchanges must be made
between the blood and cells at capillaries
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RESPIRATORY VOLUMES AND CAPACITIES
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Many factors affect respiratory capacity – size, sex,
age, and physical condition
Normal quiet breathing moves approx. 500ml of air
into and out of the lungs with each breath (tidal
volume)
The amount of air that can be taken in above the tidal
volume is the inspiratory reserve volume (IRV)
The amount of air that can be forcibly exhaled after a
tidal expiration is the expiratory reserve volume
(ERV)
Residual volume – amount of air that still remains in
the lungs after expiration (allows for gas exchange to
go on continuously between breaths)
RESPIRATORY VOLUMES AND CAPACITIES
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Vital capacity = TV + IRV + ERV
Dead space volume – air that enters and remains
in the passageways and never reaches the alveoli
Spirometer – measures respiratory capacities
Spirometer testing is useful for evaluating losses
in respiratory functioning and respiratory
illnesses (pneumonia & emphysema)