RESPIRATORY SYSTEM HISTOLOGY LABORATORY

1
RESPIRATORY SYSTEM HISTOLOGY LABORATORY

• The respiratory system includes the lungs and a
  system of passages that link the site of gas
  exchange with the external environment. It is
  customary to divide the respiratory system into 2
  principle regions
• a conducting portion, consisting of the nasal
  cavity, nasopharynx, larynx, trachea, bronchi,
  bronchioles, and terminal bronchioles.
• a respiratory portion, consisting of respiratory
  bronchioles, alveolar ducts, and
  alveoli.Initially, the patency of the airways is
  maintained by the presence of hyaline cartilage
  (larynx, trachea, extrapulmonary and
  intrapulmonary bronchi). Thereafter the patency
  of the airways is maintained by the elasticity of
  the lungs.There are changes in the epithelial
  lining of the respiratory tree as one proceeds
  from the nasal cavity to the alveoli of the
  lungsPseudostratified Columnar gt Simple
  Columnar gtSimple Cuboidal gt Simple Squamous.

2
Nasal Cavity. The cavity is divided into left and
right halves by the nasal septum. The septal wall
of each half is smooth the lateral wall is
convoluted by the superior, middle, and inferior
chonchae that project medially. The epithelium of
the nasal cavity proper is subdivided into the
Olfactory (Red) and Respiratory zones (Green).
3
Olfactory Epithelium. This is a low magnification
of olfactory epithelium from the roof of the
nasal cavity. A seromucous Bowman's gland is
illustrated in the lamina propria. Its duct opens
onto the surface. The secretions of these glands
provides a solvent for the olfactory stimulus and
washes the olfactory receptors to prevent
stagnation of the odor.
4
                                                                                      
                                                                                      
5
Olfactory Epithelium. This is a higher
magnification of the olfactory zone illustrating
the pseudostratified columnar olfactory
epithelium. The dendrites of the olfactory cells
are indicated by the RED arrows.
6
                                                                                      
                                                                                      
7
Olfactory Epithelium. Higher magnification of
olfactory epithelium. The dendrites of the
olfactory cells are indicated by the RED arrows.
The nuclei of these cells are closest to the
lumen. The nuclei of the supporting cells are
about the midline of the epithelium. The nuclei
of the basal cells are the ones closest to the
basal lamina.
8
                                                                                      
                                                                                      
9
Respiratory Epithelium. The epithelium encircled
in RED is from the "Respiratory Zone" of the
nasal cavity. It is classified as
pseudostratified ciliated columnar epithelium
with goblet cells or simply respiratory
epithelium. The goblet cells are not as obvious
as they are in the trachea and bronchi.
10
(No Transcript)
11
This is a diagramatical cross-section of the
trachea. It consists of a mucosa, submucosa,
cartiage layer, and adventitia. The inner mucosa
consists of respiratory epithelium
(pseudostratified ciliated columnar with goblet
cells) and a lamina propria of loose connective
tissue. The submucosa consists of a denser
connective tissue containing seromucous glands
that open onto the mucosal surface by means of a
duct. External to the submucosa is a C-shaped
hyaline cartilage. Posterior to the hyaline
cartilage and spanning the open end of the
cartilage is a small band of smooth muscle cells,
the trachealis muscle. Outermost, the adventitia
consists of a dense connective tissue. The
adventitia binds the trachea to other structures
(e.g. esophagus),
12
Trachea. This section is through the outer
portion of the trachea. The trachea is surrounded
by an adventitia of dense connective tissue which
helps to bind this organ to other structures.
Inner to the adventitia is the C-shaped hyaline
cartilage which helps to maintain the patency of
the trachea.
13
                                                                                      
                                                                                      
14
Trachea. Illustrated is the mucosal lining of the
trachea. It consists of respiratory epithelium
(pseudostratified ciliated columnar epithelium
with goblet cells) and a lamina propria. The
yellow line shows the separation between the two.
The epithelial nuclei closest to the lumenal
surface are those of the ciliated and brush cells
while those closest to the basal lamina belong to
the basal and the small granual cells.
15
                                                                                      
                                                                                      
16
Intrapulmonary Bronchus. This is a low
magnification of a section through the lung. The
clear spaces fillingmost of the image are the air
spaces associated with alveoli. The large airway
identified by the "X" is an intrapulmonary
bronchus which maintains its patency by virtue of
cartilagenous "plates" within its walls. This
will be obvious on the next image.
17
                                                                                      
                                                                                      
18
This structure is identified as an intrapulmonary
bronchus due to the presence of alveoli and the
presence of cartilagenous plate within its wall.
19
                                                                                      
                                                                                      
20
This image image can be identified as an
intrapulmonary bronchus due to the presence of
alveoli and hyaline cartilage. This airway is
lined by respiratory epithelium. Note the smooth
muscle bands located between the lamina propria
and the submucosa.
21
                                                                                      
                                                                                      
22
Bronchiole. Intrapulmonary bronchi undergo
several generations of branching and become
reduced in diameter as a result of the
branchings. When they reach about 1mm in
diameter, they lose their cartilage plates and
become known as bronchioles. These structures are
lined by respiratory epithelium and contain
obvious bands of smooth muscle in their walls.
The patency of bronchioles is maintained by the
elasticity of the lung.
23
                                                                                      
                                                                                      
24
Bronchiole. This is a higher magnification of the
previous slide illustrating a section through a
bronchiole. This can be identified as such even
at this magnification due to (1) alveoli, (2)
respiratory epithelium lining (PSCC), (3) a
lack of cartilage.
25
                                                                                      
                                                                                      
26
Terminal bronchiole. Terminal bronchioles (X)
represent the final section in the conducting
portion of the respiratory tree. WHile not
obvious in this section, they are lined by a
simple cuboidal epithelium.
27
                                                                                      
                                                                                      
28
Terminal Bronchiole. At this magnification, the
terminal bronchiole is easily identified by its
reduced height of epithelium. These structures
are lined by a simple cuboidal epithelium some of
which are ciliated. The non-ciliated cuboidal
cells are either Clara or brush cells.
29
                                                                                      
                                                                                      
30
Terminal Bronchiole. Higher magnification of the
previous slide. Note the simple cuboidal
epithelium, especially the Clara cell. These
cells tend to be lightly stained due to the
lipoproteins in the cytoplasm.
31
                                                                                      
                                                                                      
32
This image shows a cross-section of a terminal
bronchiole (TB) with a respiratory bronchiole
(RB) branching off of it. Respiratory bronchioles
represent the beginning of the "respiratory"
portion of the respiratory tree and is
characterized as having "outpocketings" of the
wall (arrows). These outpocketings are alveoli
respresenting sites of gas exchange between the
air and blood.
33
                                                                                      
                                                                                      
34
Respiratory Bronchiole. This is a low
magnification cross section of an airway that can
be identified as a respiratory bronchiole (X) due
to the presence of "outpocketings" (aveoli) in
its walls.
35
                                                                                      
                                                                                      
36
This is a high magnification of the previous
slide illustrating the alveoli of the respiratory
bronchiole. The epithelium consists of simple
ciliated epithelium plus Clara cells.
37
                                                                                      
                                                                                      
38
The upper portion of the image shows a terminal
bronchiole (B) and longitudinal cuts through two
respiratory bronchioles (RB) branching off of it.
The area encircled in red is enlarged on the next
page.
39
                                                                                      
                                                                                      
40
The lower portion of the image represents the
lumen of a respiratory bronchiole. Groups of
smooth muscle cells (SM) form the wall of this
bronchiole and control the lumenal diameter of
this structure. Activities of the smooth muscle
cells are due in part to the response to
seratonin and dopamine secreted by small granule
cells.
41
                                                                                      
                                                                                      
42
Alveolar Duct. Alveolar ducts branch off of
respiratory bronchioles. Unlike the previous
parts of the airway system, alveolar ducts to not
have walls of their own but consist of a linear
sequence of alveoli. Alveolar ducts terminate as
alveolar sacs. The area encircled in red shows a
small cluster of alveoli.
43
                                                                                      
                                                                                      
44
Alveolar Septum. No image is available at this
time. Refer to your atlas for an image of
alveolar septa noting type I II pneumocytes,
capillaries, and macrophages.
45
(No Transcript)
46
(No Transcript)