Download Respiratory system note outline

Chapter 19
Respiratory System
Respiration is the process of exchanging gases between the
atmosphere and body cells. Consists of the following
events:
•  ventilation
•  external respiration
•  transport
•  internal respiration
•  cellular respiration
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Organs of the
Respiratory System
• The respiratory system consists of
the passages that filter incoming air
and transport it to the many
microscopic air sacs where gases are
exchanged
• Role of the respiratory system is to
provide oxygen for aerobic
respiration and to eliminate carbon
dioxide rapidly enough to maintain
the pH of the internal environment
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Organs of the
Respiratory System
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1
Upper Respiratory Tract
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Upper Respiratory Tract
• Nose
• Nostrils (external nares) - openings to the respiratory
system
• Has hairs to trap large particles
• Nasal cavity-hollow space behind the nose
• Nasal septum-divides the nasal cavity medially into right
and left parts
• Nasal conchae-divide the nasal cavity into superior, middle
and inferior meatuses
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Mucous in Respiratory Tract
Cilia move mucus and trapped particles from the nasal cavity
to the pharynx
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Sinuses
Air-filled spaces in maxillary, frontal, ethmoid, and
sphenoid bones that light the skull and act as resonating
chambers
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Pharynx
• Connect the nasal
cavity with the larynx
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Larynx
Voice box
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Vocal Cords
• Epiglottis-closes the
larynx when a person
swallows
• Glottis-opening to the
larynx
• True vocal cords
vibrate to produce
sound
• Pitch is controlled
by tension
• Intensity
(loudness) is
controlled by the
force of air
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Trachea
• Windpipe, flexible
cylindrical tube 2.5 cm
in diameter by 12.5 cm
long
• Connects the larynx
with the bronchi
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Tracheostomy
Performed to allow air to bypass an obstruction
within the larynx
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Bronchial Tree
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Alveoli
• 300 million
• 170-180 square
meters of surface
area
• Gas exchange
occurs here
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Diffusion Across Respiratory
Membrane
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Lungs
• Soft, spongy, coneshaped organ
• Lobes
• lobules
• Hilum-where bronchi
and blood vessels enter
and leave lungs
• Pleural cavity -space
containing lungs
• Lined with the
pleura(visceral,
parietal)
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Breathing Mechanism
•  Breathing or ventilation is the movement of air
from outside the body into the bronchial tree and
alveoli
•  air movements of inspiration and expiration
•  changes in the size of the thoracic cavity due
to changes in pressure
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Inspiration
•  Moving the
plunger of a syringe
causes air to move in
or out
•  Air movements in
and out of the lungs
occur in much the
same way
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Lungs at Rest
When lungs are at rest, the pressure on the inside of the
lungs is equal to the pressure on the outside of the thorax
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Inspiration
•  Intra-alveolar
pressure decreases to
about 758mm Hg as
the thoracic cavity
enlarges
•  Atmospheric
pressure forces air
into the airways
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Inspiration
Shape of thorax at end
of normal inspiration
Shape of thorax at end of maximal
inspiration aided by contraction of
sternocleidomastoid and pectoralis minor
muscles
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Expiration
•  due to elastic recoil of the lung tissues and abdominal organs
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Maximal Expiration
•  contraction of
abdominal wall
muscles
•  contraction of
posterior internal
intercostal muscles
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Respiratory Volumes and
Capacities
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8
Alveolar Ventilation
minute ventilation
•  tidal volume
multiplied by
breathing rate
•  amount of air that is
moved into the
respiratory
passageways
alveolar ventilation rate
•  major factor affecting
concentrations of oxygen
and carbon dioxide in the
alveoli
•  volume of air that
reaches alveoli
•  tidal volume minus
physiologic dead space
then multiplied by
breathing rate
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Nonrespiratory Air Movements
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Alveoli
•  gas exchanges between the air and blood
occur within the alveoli
•  alveolar pores allow air to pass from one
alveolus to another
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Respiratory Membrane
•  consists of the walls of the alveolus and the capillary
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Diffusion Through
Respiratory Membrane
Gases are exchanged between alveolar air and capillary
blood because of differences in partial pressure
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Oxygen Transport
•  Most oxygen binds to hemoglobin to form oxyhemoglobin
•  Oxyhemoglobin releases oxygen in the regions of body cells
•  Much oxygen is still bound to hemoglobin in the venous blood
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Carbon Dioxide Transport
•  dissolved in plasma
•  combined with hemoglobin
•  in the form of bicarbonate ions
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Life-Span Changes
•  reflect accumulation of environmental influences
•  reflect the effects of aging in other organ systems
•  cilia less active
•  mucous thickens
•  swallowing, gagging, and coughing reflexes slow
•  macrophages in lungs lose efficiency
•  increased susceptibility to respiratory infections
•  “barrel chest” may develop
•  bronchial walls thin and collapse
•  dead space increases
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Clinical Application
The Effects of Cigarette Smoking on the
Respiratory System
•  cilia disappear
•  excess mucus produced
•  lung congestion increases lung
infections
•  lining of bronchioles thicken
•  bronchioles lose elasticity
•  emphysema fifteen times more
common
•  lung cancer more common
•  much damage repaired when
smoking stops
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