Histology of trachea and lung

2. HISTOLOGY OF TRACHEA AND
LUNG
Dr.ushakannan,Asst.professor.

3. RESPIRATORY SYSTEM
 Conducting Part-
responsible for passage of
air and conditioning of the
inspired air.
Examples:nasal
cavities,pharynx, trachea,
bronchi and their
intrapulmonary
continuations.
 Respiratory Part-involved
with the exchange of
oxygen and carbondioxide
between blood and inspires
air.Includes the lungs

4. Trachea
 Left and Right lobar bronchus Lungs.
 Lobar Bronchi. . Lobes(Right 3 and Left 2.).
 Segmental bronchi Broncho-pulmonary
segments(10+10)
 Bronchioles
 Terminal bronchioles.
 Respiratory Bronchioles.
 Alveolar ducts Alveolar sacs Alveoli.

5. RESPIRATORYSYSTEM
HISTOLOGY
 Trachea
 Bronchus
-Primary bronchus
-Secondary bronchus
-Tertiary bronchus
 Bronchiole
 Lung

6. Trachea
 Mucosa
-Epithelium
-Lamina propria
 Sub mucosa
 Cartilage &muscle
layer
 Adventitia

7. RESPIRATORY EPITHELIUM

8. Trachea
Mucosa
 Epithelium
-Pseudo stratified ciliated
columnar/ Respiratory
epithelium
Cells-Ciliated columnar cells
- Goblet cells
-Brush cells
- Basal cells
-Granule (kulchitsky)
cells
Secretory cells -Clara cells(
bronchiolar cells) surfactant.
 Lamina propria - Elastic
fibre, Lymphocyte, Mast
cells, Blood vessels

10. Trachea
 Sub mucosa-
 Loose connective tissue
 Tracheal glands-Mixed
(serous &mucus) glands
 Blood vessels and ducts
 Cartilage &smooth muscle
layer-
 ”C” Shaped hyaline cartilage
having perichondrium and
chondrocytes
 Ends of cartilage connected by
smooth muscles
 Adventitia-fibro elastic tissue

11. TRACHEA (T.S. LOW POWER)

12. CELLS SEEN IN THE
RESPIRATORY PASSAGES
 Goblet cells
 Non-ciliated serous cells
 Basal cells
 Cells of Clara
 Brush cells
 Argyrophil Cells similar to diffuse endocrine cells
of gut
 Lymphocytes

13. HISTOLOGY OF LUNG

14. BRONCHUS
 Principal bronchus
-same as trachea
 Secondary /Lobar
 bronchus
-Irregular hyaline cartilage
-Pseudo stratified ciliated
columnar
 Tertiary /Segmental
bronchus
-Columnar epithelium
-Patches of cartilage

16.  Segmental or tertiary bronchus:
 The number of Goblet cells reduced.(epithelium)
 The number of Glands reduced.(submucosa)
 The cartilage is present in the irregular plates.

17. BRONCHIOLE
 Terminal bronchiole
-Columnar epithelium
-No cartilage
- smooth muscle +
-Clara cells (dome shaped)
present
-Cuboidal epithelium
-No mucous gland
 Respiratory bronchiole

18. RESPIRATORY BRONCHIOLE
 Cuboidal epithelium.
 No mucus gland.

19.  Lined by simple ciliated or columnar epithelium.
 Smooth muscles form ring underneath the epithelium in
between two adjacent alveoli.

20.  Alveolar duct-Alveolar sac.
 Alveolar duct lined by simple squamous epithelium.
 Increase the surface area of gaseous exchange.
 Surrounded by network of capillaries.

22.  Inter alveolar septum-
Is the wall present in between the two adjacent alveoli.
 Consists of epithelial cells of each alveolus on both sides.
 Connective tissues contain capillaries,collagen,elastic
fibres,fibroblasts and macrophages(dust cells).

23.  Alveoli are thin walled outpouchings , lined by a
single layer of cells.
 Two types:
 Pneumocyte 1 and2 cells.
 Also called pneumocyte or alveolar cells.

24.  Type 1 Pneumocyte are squamous cells ,adjacent cells are
joined together by tight junctions.
 Function: Gaseous exchange.
 Type 11 Pneumocytes:
 Cuboidal cells,scattered among type 1 cells.
 Secrete Pulmonary surfactant which lowers the surface
tension and prevents alveoli from collapsig.
 Alveolar macrophages or Dust cells – Remove debris.

25. Bronchus and Bronchiole

26. DIFFERENCES BETWEEN BRONCHI
AND BRONCHIOLES
 Bronchus
 Glands are present.
 Presence of cartilage.
 Goblet cells are present.
 Spiraliy arranged smooth
muscle layer.
 Mucosa folded lined by
ciliated pseudostratified
columnar cells.
Bronchioles
 No glands
 No cartilage
 No goblet cells
 Thick smooth muscle
layer
 Mucosa highly folded
lined by simple columnar
or cuboidal cells with
Presence of Clara cells
 Many elastic fibres

56. Trachea (T.S. Low Power)