CHAPTER 11
Respiratory System
203
Figure 11-1.
Overview of the respiratory system.
The
respiratory system
plays the essential role of supplying oxygen to the body. It can be divided into the
upper respiratory airway
and
lower respiratory airway
; functionally, the respiratory system can also be divided into a
conducting portion
and
respiratory por-
tion
.
Upper respiratory airway infection
is a common term in clinical diagnosis. The
upper respiratory airway
consists of the
nasal
cavity
,
nasopharynx
,
oropharynx
, and
larynx
. There are three regions in the nasal cavity classiF
ed according to types of epithelial
covering: the
nasal vestibule
(stratiF ed squamous epithelium), the
nasal mucosa
(ciliated pseudostratiF
ed columnar epithelium), and
the
olfactory mucosa
(specialized olfactory epithelium). The nasopharynx is continuous with the oropharynx and extends to the
larynx. The larynx is composed of the
epiglottis
,
vocal cords
(
folds
), and a set of
cartilages
of complex shape. The
lower respiratory
airway
consists of the
trachea
,
bronchi
,
bronchioles
, and
alveoli
in the lungs. The skeletal support changes from
C-shaped hyaline
cartilage
in the trachea and primary bronchi to
cartilage plates
in secondary and tertiary bronchi. Bronchioles have no cartilage
support. Terminal bronchioles give rise to respiratory bronchioles. which have the function of gas exchange along with the alveoli
(see ±ig. 11-9).
Structures of the Respiratory System
I. Conducting portion
A. Upper respiratory airway
1.
Nasal cavity
a.
Nasal vestibule
b.
Nasal mucosa
c.
Olfactory mucosa
2.
Nasopharynx
3.
Oropharynx
4.
Larynx
a.
Epiglottis
b.
Vocal cords (folds)
B. Lower respiratory airway
1.
Trachea
2.
Extrapulmonary bronchi
(primary bronchi)
3.
Intrapulmonary bronchi
a.
Secondary bronchi
b.
Tertiary (segmental) bronchi
c.
Bronchioles
d.
Terminal bronchioles
II. Respiratory portion
A. Respiratory bronchiole
(respiratory portion begins)
B. Alveolar ducts and alveoli
C. Type I and II pneumocytes
D. Alveolar macrophages
Vestibule
Bronchioles
Nasal mucosa
Nasopharynx
Oropharynx
Extrapulmonary
(primary) bronchus
Larynx
Intrapulmonary
(secondary) bronchus
Intrapulmonary
(tertiary) bronchus
Alveoli
Epiglottis
Trachea
Olfactory
mucosa
previous page 218 Dongmei Cui -  Atlas of Histology with Functional and Clinical Correlations 2011 read online next page 220 Dongmei Cui -  Atlas of Histology with Functional and Clinical Correlations 2011 read online Home Toggle text on/off