1. Histology of
Respiratory System

2. Includes :
the lung
a system of tube

3. jurasicpork Divided into 2 principal regions : conducting portion :
nasal cavity, nasopharynx, larynx, trachea, bronchi, bronchioles & terminal bronchioles
respiratory portion :
respiratory bronchioles, alveolar ducts, alveoli (alveoli : the greater part of the lung)
jurasicpork

4. 28/04/2017
Respiratory Zone 4 4

5. The main divisions of the respiratory tract
The main divisions of the respiratory tract. The natural proportions of these structures have been altered for clarity; the respiratory bronchiole, for example, is in reality a short transitional structure.

6. RESPIRATORY EPITHELIUM
Ciliated Pseudostratified Columnar Epithelium
5 types of cell :
1. ciliated columnar epithelium
2. mucous goblet cells
3. brush cells
4. basal cells
5. small granule cells
Photomicrograph illustrating the main components of the respiratory epithelium. Pararosaniline—toluidine blue (PT) stain. High magnification.

8. wanted !!!

9. NASAL CAVITY Consists of : - vestibule (external)
- nasal fossae (internal)
VESTIBULE
Is the most anterior and dilated portion of nasal cavity
Numerous sebaceous & sweat glands, vibrisae
Within the vestibule  keratinized (-)  respiratory epithelium before entering the nasal fossae

10. - superior : specialized olfactory epithelium - middle respiratory
NASAL FOSSAE
Conchae :
- superior : specialized olfactory epithelium
- middle respiratory
- inferior epithelium
The olfactory epithelium  olfactory chemoreceptor located
Ciliated Pseudostratified Columnar Epithelium
3 types of cells :
1. supporting cells
2. basal cells
3. olfactory cells
Olfactory mucosa showing the 3 cell types (supporting, olfactory, and basal) and a Bowman’s gland.

13. PARANASAL SINUSES
Closed cavities in the : frontal, maxillary, ethmoid, sphenoid bones
Lined with a thinner respiratory epithelium, few goblet cells
Communicate with nasal cavity through small openings
Mucous product  drain in to the nasal passages by ciliated epithelial cells

14. NASOPHARYNX
First part of the pharynx
Lined with respiratory epithelium

15. LARYNX Connects the pharynx to the trachea
The larger cartilge : hyaline cartilage
The smaller cartilage : elastic cartilage
Cartilage participate in producing sounds for phonation
Below the epiglottis : - false vocal sound
- true vocal sound

17. TRACHEA Mucosa : - Ciliated Pseudostratified Columnar Epithelium
with goblet cells
- Lamina propria
Sub mucosa : loose connective tissue
Hyaline cartilage : C-shaped rings
Smooth muscle fibers
Adventisia (fibrosa)

20. Section of trachea showing the respiratory epithelium with goblet cells and columnar ciliated cells. Also shown are serous glands in the lamina propria and hyaline cartilage. The mucous fluid produced by the goblet cells and by the glands forms a layer that permits the ciliary movement to propel foreign particles out of the respiratory system. PT stain. Medium magnification.

21. Light photomicrograph of the trachea in a monkey (´270)
 Light photomicrograph of the trachea in a monkey (´270). There are numerous cilia (Ci) as well as goblet cells (GC) in the epithelium. Also observe the mucous glands (MG) in the subepithelial connective tissue and the hyaline C-ring (HC) in the adventitia. L, lumen; PC, perichondrium.

24. BRONCHIAL TREE TRACHEA BRONKUS PRIMER BRONKUS PRIMER
ka : 3 CAB. BRONKUS ki : 2 CAB. BRONKUS
BRONKIOLUS
BRONCHIOLUS TERMINALIS
BRONCHIOLUS RESPIRATORIUS
DUCTUS ALVEOLARIS
ALVEOLUS ALVEOLUS

25. BRONCHUS
Ф ± 5 mm
Mucosa : similar to the mucosa of the trachea (Ciliated Pseudostratified Columnar Epithelium)
The bronchial cartilage are more irregular shape
Larger bronchi : cartilage rings completely encircle the lumen
Smaller bronchi : cartilage rings are replaced with isolated plates or islands of hyaline cartilage
Lamina propria : smooth muscle layer, rich in elastic fiber, abundance of mucous & serous gland  ducts  bronchial lumen

27. PSEUDOSTRATIFIED COLUMNAR EPITHELIUM
CARTILAGE
MUSCULARIS
ADIPOSE TISSUE

28. Hyaline cartilage

31. BRONCHIOLES Ф ≤ 5 mm Mucosa : - cartilage & glands (-)
- scattered goblet cells
TERMINAL BRONCHIOLES
RESPIRATORY BRONCHIOLES

34. TERMINAL BRONCHIOLES
Ciliated Pseudostratified Columnar Epithelium  Ciliated Simple Columnar Epithelium  Ciliated Simple Cuboidal Epithelium
Clara cells :
- (-) cilia
- (+) secretory granules in their apex
- secrete protein  protect the bronchiolar lining
against oxidative pollutants and inflamation
- lamina propria : smooth muscle, elastic fiber

35. Clara cells in the epithelium of a terminal bronchiole
Clara cells in the epithelium of a terminal bronchiole. These cells show secretory granules and a bulging apical cytoplasm.
PT stain. High magnification.

37. RESPIRATORY BRONCHIOLES
Transition between conducting and respiratory
Mucosa : identical to the terminal bronchioles, except their walls are interrupted by numerous sacklike alveoli  proceeding distally  alveoli »
Ciliated Cuboidal Epithelium & Clara cells
Smooth muscle and elastic fiber

38. Section of a terminal bronchiole with a small portion of a respiratory bronchiole continuous with an alveolar duct and many alveoli. PT stain. Low magnification.

41. ALVEOLI

42. ALVEOLAR DUCTS
Proceeding distally  the number of alveolar openings »  alveolar ducts
Alveolar duct & alveoli lined with squamous cells
Lamina propria : smooth muscle  disappears at the distal ends of alveolar ducts
Alveolar ducts  atria that communicate with alveolar sacs
Elastic fiber :
enable the alveoli to expand
contract passively with expiration
Reticular fibers :
prevent overdistention
prevent damage to the delicate capillaries and thin alveolar septa

44. Transition of a terminal bronchiole into an alveolar duct (arrow)
Transition of a terminal bronchiole into an alveolar duct (arrow). Note the Clara cells (arrowheads). PT stain. Medium magnification.

45. ALVEOLUS
Sacklike evaginations of the respiratory bronchioles, alveolar ducts, alveolar sacks
Resemble small pockets that are open on one side similar to the honeycombs of a beehive
Exchange of O2 and CO2 between air & blood
Each wall lies between 2 alveoli  interalveolar septum
An interalveolar septum consists of 2 thin squamous epithelial layers :
type I cells = squamous alveolar cells
type II cells = surfactant cells

50. TYPE I CELLS
Line the alveolar surface
Cells are so thin (25nm)
Desmosomal & occluding junctions  prevent leackage of tissue fluid into alveolar air space
To provide a barrier minimal thickness that is readily permeable to gases

51. TYPE II CELLS
Interspersed among the type I cells
Desmosomal and occluding junctions
Divided by mitosis replace type I & II population
Exhibit a characteristic vesicular or foamy cytoplasm, by presence of lamellar bodies
Lamellar bodies  pulmonary surfactant  alveolar surface tension ↓
Without surfactant  alveoli collaps (expiration)
Surfactant appears in the last week of gestation

52. Secretion of surfactant by a type II cell
Secretion of surfactant by a type II cell. Surfactant is a protein-lipid complex synthesized in the rough endoplasmic reticulum and Golgi complex and stored in the lamellar bodies. It is continuously secreted by means of exocytosis (arrows) and forms an overlying monomolecular film of lipid covering an underlying aqueous hypophase. Occluding junctions around the margins of the epithelial cells prevent leakage of tissue fluid into the alveolar lumen.

53. LUNG MACROPHAGE = alveolar macrophage = dust cells
Found in the anterior of the interalveolar septum, often seen on the surface of the alveolus
The alveolar macrophage never passed through the epithelial lining that scavenge the outer surface of the epithelium  carried to the pharynx  swallowed

55. ALVEOLAR PORES To connect neighboring alveoli
Equalize air pressure in the alveoli
Promote the collateral circulation of air when a bronchiole is obstructed

56. BLOOD AND LYMPH CIRCULATION
Blood and lymph circulation in a pulmonary lobule. Both vessels and bronchi are enlarged out of proportion in this drawing. In the interlobular septum, only one vein (on the left) and one lymphatic vessel (on the right) are shown, although both actually coexist in both regions. At the lower left, an enlargement of the pleura shows its mesothelial lining. (Modified and reproduced, with permission, from Ham AW: Histology, 6th ed. Lippincott, 1969.)