Download The general features of respiratory system

GENERAL FEATURES
OF UPPER & LOWER
RESPIRATORY SYSTEM
LEARNING OBJECTIVES
At the end of this lecture, students should be know:
 The general features of respiratory system
 Structural and functional classifications of respiratory
system
 The general structure, function and role of each organ
making up the respiratory system
INTRODUCTION
The respiratory system serves 3 principal purposes in the
human body:

gaseous exchange

sound production
It can be divided into
 2 structural divisions:
upper & lower
 2 functional divisions:
conducting & respiratory
Respiration involves 3 separate inter-related functions:
 Ventilation (breathing):
Delivery of Oxygen (in air) to
the alveoli of the lungs
 Gaseous Exchange:
Exchange of gases between the
alveoli and the blood
 Oxygen Utilization:
Exchange of gases between the
blood and tissue (cellular
respiration)
Ventilation and gaseous
exchange at the air blood interface are collectively known as
external respiration
Gaseous exchange between the blood and
tissues is known as internal respiration
(oxygen utilization).
STRUCTURE OF RESPIRATORY
SYSTEM
The respiratory system is composed of :
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The nasal cavity
Pharynx
L a r yn x
Trachea
The bronchi
Bronchioles
Pulmonary alveoli in the lungs
STRUCTURAL
CLASSIFICATION
Upper respiratory system:
 The nose
 The pharynx
 The larynx
Lower respiratory system:
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Trachea
Bronchial tree
Alveoli and the lungs.
FUNCTIONAL CLASSIFICATION
Conducting part: in which gases are transported to the alveoli
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Nasal cavities
Pharynx
Larynx
Trachea
Bronchi & terminal bronchioles
Respiratory division: where gaseous exchange takes place between the atmosphere
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and the blood.
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
pulmonary atria & alveoli.
Consists of 2 structures:
 External – vestibule
 Internal - nasal fossae
NOSE
VESTIBULE:
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Most anterior & dilated part of nasal cavity.
Inner surface of nares (nostrils) have:
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sebaceous & sweat glands
thick short hair (vibrissae) that filter out large particles
from the inspired air.
NASAL FOSSAE:
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Two chambers separated by nasal septum.
3 bony shelf-like projections extend from each lateral wall known as
conchae.
Superior Conchae are covered by olfactory epithelium.
Middle & inferior conchae are covered by respiratory epithelium
PHARYNX
Divided into:
 Nasopharynx and oropharynx
 Lined with respiratory epithelium.
LA R Y NX
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Connects the pharynx to
the trachea.
Lamina propria contains 9
cartilages:
 3 unpaired
 Thyroid
 Cricoid
 epiglottis
 3 paired
 Arytenoids
 Corniculate
 Cuneiform
LARYNGEAL EPITHELIUM
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Lining epithelium varies in type in different parts of
the larynx:
stratified squamous noncornified epithelium covers:
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laryngeal inlet
most of the epiglottis
true vocal cords.
Typical respiratory epithelium (i.e., pseudostratified
columnar ciliated epithelium with goblet cells)
covers:
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the rest of the larynx.
LARYNX
TRACHEA
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10 cm long
extends from the base of the
larynx to sternal angle (2nd
costal cartilage/ T4 vertebrae)
At sternal angle bifurcates into
two primary bronchi.
Respiratory epithelium with
numerous goblet cells.
Lamina Propria contains 16-20
C-shaped rings of hyaline cartilage
Gaps b/w posterior ends of each cartilage is bridged by a band of fibro-elastic
ligament & bundle of smooth muscle called Trachealis
BRONCHI
Extra-pulmonary or primary bronchi
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Resembles the trachea
D-shaped
smaller diameter.
Intra-pulmonary or secondary bronchi
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It differs from the Extra-pulmonary by:
Smaller diameter
round contour.
Smooth muscles appear in the form of complete ring.
Hyaline cartilage occur as irregular cartilaginous plates
BRONCHIOLES
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1 mm or less diameter
Gradual changes occurs in the epithelium as
follows:
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First simple columnar
Then simple cuboidal ciliated epithelium.
They differ from the bronchi in 2 respect:
No cartilage in their wall.
No glands in their mucosa.
TERMINAL BRONCHIOLES: (0.5 mm diameter)
Epithelium simple cuboidal with no goblet cells
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Has scattered non-ciliated, dome-shaped clara cells.
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RESPIRATORY BRONCHIOLES:
Transitional zone between conducting and respiratory
divisions
Distinguishing feature is presence of saccular outpocketing (alveoli) on its wall.
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ALVEOLAR DUCTS
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Thin walled conical tubes
Wall studded with alveolar sacs & alveoli
Alveoli open into the lumen of the duct
Epithelium – simple squamous
Lamina propria - consists of smooth muscle & C.T.
Terminate by opening into the pulmonary atria
ATRIA :
 Irregular spaces, from which alveolar sacs & alveoli diverge.
 Two or more alveolar sacs arise from each atrium.
 A network of elastic and
fibers encircles the openings of
alveolar sacs and alveoli.
 No smooth muscle in the wall of
and alveolar sacs.
reticular
atria,
ALVEOLAR (AIR) SAC:
 Collection of alveoli opening
central chamber.
into a
PULMONARY ALVEOLI
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the atria
Sac-like evaginations (~200 µm in diameter) of the respiratory bronchioles,
alveolar ducts & sacs.
Terminal portion of the bronchial tree
Lined by 2 types of epithelial cells:
Squamous alveolar cells or type – I cells.
Great alveolar cells or type – II cells or septal cells.
Main sites where exchange of oxygen & carbon dioxide take place between the
inspired air & blood.
RESPIRATORY DIVISION