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PowerPoint® Lecture Slides
prepared by
Janice Meeking,
Mount Royal College
CHAPTER
22
The Respiratory
System:
Part A – anatomy
and histology
Copyright © 2010 Pearson Education, Inc.
Major Functions of the Respiratory System
• To supply the body with oxygen and dispose of carbon
dioxide
• Respiration – four distinct processes must happen
• Pulmonary ventilation (breathing):
movement of air into and out
of the lungs
• External respiration: O2 and CO2
exchange between the lungs
and the blood
• Transport: O2 and CO2
in the blood
• Internal respiration: O2 and CO2
exchange between systemic blood
vessels and tissues
Copyright © 2010 Pearson Education, Inc.
Respiratory
system
Circulatory
system
Respiratory System – conducting and respiratory zone
• Consists of the respiratory and conducting zones
• Respiratory zone:
• Site of gas exchange
• Consists of respiratory bronchioles, alveolar ducts, and
alveoli
• Conducting zone:
• Conduits for air to reach the sites of gas exchange
• Includes all other respiratory structures (e.g., nose,
nasal cavity, pharynx, trachea)
• Respiratory muscles – diaphragm and other muscles that
promote ventilation
Copyright © 2010 Pearson Education, Inc.
Respiratory System – conducting and respiratory zone
• Conducting passageways carrying air to and from the alveoli
• Upper respiratory passages filter and humidify incoming air
• Lower passageways include delicate conduction passages and
alveolar exchange surfaces
• The conducting passageways of the respiratory system (nasal cavity,
trachea, bronchi and bronchioles) are lined by ciliated
pseudostratified columnar ET, which includes mucus-secreting goblet
cells.
• Because the passage of air depends on wide open passageways, the
larger respiratory passages (trachea and bronchi) are supported by
rings of cartilage.
• The respiratory regions are lined with simple squamous ET
Copyright © 2010 Pearson Education, Inc.
Function of the Nose
• The only externally visible part of the respiratory system
that functions by:
• Providing an airway for respiration
• Moistening and warming the entering air
• Filtering inspired air and cleaning it of foreign matter
• Serving as a resonating chamber for speech
• Housing the olfactory receptors
Copyright © 2010 Pearson Education, Inc.
Paranasal Sinuses
• Sinuses in bones that surround the nasal cavity
• Sinuses lighten the skull and help to warm and
moisten the air
http://sinusitis.upmc.com/Images/Sub/PhotoSinusitis.jpg
Copyright © 2010 Pearson Education, Inc.
Larynx (Voice Box)
• Attaches to the hyoid bone and opens into the
laryngopharynx superiorly
• Continuous with the trachea posteriorly
• The functions of the larynx are:
• Air passage
• To act as a switching mechanism to route air and
food into the proper channels
• To function in voice production
Copyright © 2010 Pearson Education, Inc.
Framework of the Larynx
• Cartilages (hyaline) of the larynx
• Shield-shaped anterosuperior thyroid cartilage with
a midline laryngeal prominence (Adam’s apple)
• Signet ring–shaped anteroinferior cricoid cartilage
• Three pairs of small arytenoid, cuneiform, and
corniculate cartilages
• Epiglottis – elastic cartilage that covers the laryngeal inlet
during swallowing
• Glottis is the superior opening of the larynx. It is guarded
by the epiglottis (cartilage)
Copyright © 2010 Pearson Education, Inc.
Vocal Ligaments
• Attach the arytenoid cartilages to the thyroid cartilage
• Composed of elastic fibers that form mucosal folds called
true vocal cords
• The medial opening between them is the glottis
• They vibrate to produce sound as air rushes up
from the lungs
• False vocal cords
• Mucosal folds superior to the true vocal cords
• Have no part in sound production
Copyright © 2010 Pearson Education, Inc.
Voice Production
• Speech: release of expired air while opening and
closing the glottis
• Pitch is determined by the length and tension of the
vocal cords
• Loudness depends upon the force of air
• Chambers of pharynx, oral, nasal, and sinus cavities
amplify and enhance sound quality
• Sound is “shaped” into language by muscles of the
pharynx, tongue, soft palate, and lips
Copyright © 2010 Pearson Education, Inc.
Trachea
•
Flexible and mobile tube extending from the larynx
into the mediastinum
•
Composed of three layers
•
Mucosa – ciliated pseudostratified columnar
epithelium with goblet cells
•
Submucosa – connective tissue with mucous
glands, lymph nodes
•
Adventitia – fibrous CT that contains C-shaped
rings of hyaline cartilage
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The primary bronchi
• Trachea branches in the mediastinum into right and left
primary bronchi
• Bronchi enter the lungs at the hilus
• Have C-shaped cartilaginous supporting rings
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The bronchial tree
• System of tubes formed from the primary bronchi and
their branches
• Primary bronchi branch into secondary or lobar bronchi
• Secondary bronchus goes to each lobe of the lungs
• Secondary bronchi branch into tertiary (segmental)
bronchi
• Both secondary and tertiary bronchi are covered by
overlapping plates of cartilage and not rings
• Cartilage in walls decrease and smooth muscle
increase with branching
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The bronchioles
• Branching of the bronchi that are 1 mm or less in
diameter and lack cartilage. Bronchioles are surrounded
by smooth muscle that allows the change of diameter.
• Ultimately bronchioles branch into the final branch of the
conducting division - terminal bronchioles with a
diameter of 0.3-0.5 mm
• Terminal bronchiole becomes respiratory bronchioles –
the beginning of the respiratory division
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Respiratory Zone
• Defined by the presence of alveoli; begins as terminal
bronchioles feed into respiratory bronchioles
• Respiratory bronchioles lead to alveolar ducts, then to
terminal clusters of alveolar sacs composed of alveoli
• Approximately 300 million alveoli:
• Account for most of the lungs’ volume
• Provide tremendous surface area for gas exchange
Copyright © 2010 Pearson Education, Inc.
Respiratory Membrane
• This air-blood barrier is composed of:
• Alveolar and capillary walls
• Their fused basal laminas
• Simple squamous ET (type I) – most of the cells in
the alveolus wall and are part of the respiratory
membrane (allow gas exchange)
• Septal cells (type II ) – about 5% of the alveolar wall.
The septal cells secret surfactant – a lipoprotein
secretion that reduces the surface tension in the
alveolus
• Alveolar Macrophage (dust cells) - patrol epithelium
and engulf foreign particles
Copyright © 2010 Pearson Education, Inc.
Pleurae
• Thin, double-layered serosa
• Parietal pleura
• Covers the thoracic wall and superior face of the
diaphragm
• Continues around heart and between lungs
• Visceral, or pulmonary, pleura
• Covers the external lung surface
• Divides the thoracic cavity into three chambers
• The central mediastinum
• Two lateral compartments, each containing a lung
Copyright © 2010 Pearson Education, Inc.
Dead Space
• Some of the inspired air does not contribute to the gas
exchange in the alveoli
• Anatomical dead space – volume of the conducting
respiratory passages (150 ml)
• Alveolar dead space – alveoli that cease to act in
gas exchange due to collapse or obstruction
• Total dead space – sum of alveolar and anatomical
dead spaces
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Pulmonary Function Tests
• Spirometer – an instrument consisting of a hollow bell inverted over water,
used to evaluate respiratory function
• Spirometry can distinguish between:
• Obstructive pulmonary disease – increased airway resistance
• Restrictive disorders – reduction in total lung capacity from
structural or functional lung changes
• Total/minute ventilation – total amount of gas flow into or out of the
respiratory tract in one minute
• Forced vital capacity (FVC) – gas forcibly expelled after taking a deep
breath
• Forced expiratory volume (FEV) – the amount of gas expelled
• Increases in TLC, FRC, and RV may occur as a result of obstructive disease
• Reduction in VC, TLC, FRC, and RV result from restrictive disease
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Nonrespiratory Air Movements
• Most result from reflex action
• Examples include: coughing, sneezing, crying, laughing,
hiccupping, and yawning
Copyright © 2010 Pearson Education, Inc.