The respiratory system functions to bring air into and out of the body to allow for gas exchange. It has a conducting portion made up of structures like the nasal cavity, larynx, and bronchi that warm and moisten air. The respiratory portion includes structures like the alveolar ducts and alveoli where gas exchange occurs. The respiratory tract is lined by respiratory epithelium that varies by location from ciliated columnar cells to olfactory epithelium. Structures like the nasal passages, sinuses, larynx, and trachea are described in detail including their histological makeup.

1. RESPIRATORY SYSTEM

2. Function of Respiratory System
1. Gets air into and out of the body and
allows gas exchange
2. Conducting portion
1. Nasal cavity, nasopharynx, larynx, trachea,
bronchi, bronchioles, terminal bronchioles
2. Warms, moistens air
3. Respiratory portion
1. Respiratory bronchioles, alveolar ducts,
alveoli
2. Gas exchange occurs

3. Main
Divisions of
Respiratory
Tract

4. Layers of Wall
1. Mucosa
1. Epithelium
2. Lamina propria (loose CT)
3. Smooth muscle
2. Submucosa
1. Dense irregular CT
2. Glands often present
3. Adventitia

5. Respiratory Epithelium
• In the conducting portion:
1. Ciliated columnar cells
2. Mucous goblet cells
3. Brush cells (microvilli)
1. Sensory receptor cells
4. Basal cells
1. Generative stem cells that replace other cells
5. Small granule cell (DNES)
1. Produce biogenic amines (NE, Ep, 5-HT);
paracrine
2. cells

6. Respiratory Epithelium

7. Ciliated
Columnar
Cells

8. Surface of
Respiratory
Mucosa
Ciliated cell
Goblet cell
Brush cell

9. Small Granule Cell
(DNES)
Electron micrograph of a cell
of the diffuse neuroendocrine
system. Note the
accumulation of secretory
granules (arrows) in the basal
region of the cell. The Golgi
complex seen in the upper
part of the micrograph shows
some secretory granules.

10. Nasal Passage
Turbinates

11. Nasal Cavity
• Vestibule (outer nasal area)
1. Keratinized epithelium transitions to
respiratory
2. Short hairs filter
1. Nasal Fossae
– Conchae
• Respiratory epith (pseudostratified squamous)
• Swell bodies; extensive venous system for
countercurrent flow to warm air.
• Olfactory epithelium of superior choncha

12. Nasal Mucosa
E – Epithelium
M – Mucous glands of
lamina propria
S – Serous glands of
lamina propria
V – Thin walled venules

13. Olfactory Mucosa

14. Sinuses

15. Epithelium Lining of Sinus
Thinner respiratory
epithelium that
contains few
goblet cells.

16. Respiratory Structures

17. LARYNX
Anterior Posterior

18. LARYNX

19. TRACHEA

20. Trachea
Pseudostratified Epithelium
Pseudostratified ciliated cells and mucous (goblet) cells are the two
major components of the epithelium. Cilia beat at 1,000 to 1,500 cycles
per minute resulting in movement of the mucus blanket at 0.5-1 mm
/min in small airways and 5-20 mm/min in the trachea and main
bronchi.

21. Trachea x40

22. Trachea

23. Mucous Glands in Upper Resp
Tract

24. Trachea x10

25. Trachea x10

26. Glands of Trachea x40