histology of respiratory system upper and lower The respiratory system is a complex network of organs and tissues that work together to allow you to breathe. Its primary function is to take in oxygen from the air and release carbon dioxide, a waste product of cellular respiration. The system is made up of the following: Upper respiratory tract: This includes the nose, nasal cavity, sinuses, pharynx (throat), and larynx (voice box). Lower respiratory tract: This includes the trachea (windpipe), bronchi, bronchioles, and alveoli (air sacs) in the lungs. Muscles of respiration: The diaphragm and intercostal muscles help to expand and contract the chest cavity, creating the pressure changes needed for breathing. Muscles of respiration: The diaphragm and intercostal muscles help to expand and contract the chest cavity, creating the pressure changes needed for breathing. how the respiratory system works: Inhalation: You breathe in air through your nose or mouth. The air passes through the nasal cavity, where it is warmed, humidified, and filtered. It then travels down the pharynx and into the larynx. Gas exchange: The air travels down the trachea and into the bronchi, which branch off into smaller and smaller airways called bronchioles. These eventually lead to the alveoli, tiny sacs in the lungs where gas exchange takes place. Oxygen diffuses from the alveoli into the bloodstream, while carbon dioxide diffuses from the bloodstream into the alveoli. Exhalation: You breathe out air through your nose or mouth. The air travels back up the airways and out of the body.

1. Histology of respiratory system for medical students 1

2. Histology of respiratory system for medical students 2

3. Histology of respiratory system for medical students 3

4. Histology of respiratory system for medical students 4

5. Histology of respiratory system for medical students 5

6. Histology of respiratory system for medical students 6

7. Histology of respiratory system for medical students 7

8. Histology of respiratory system for medical students 8

9. Histology of respiratory system for medical students 9

10. Histology of respiratory system for medical students 10

11. Histology of respiratory system for medical students 11

12. Histology of respiratory system for medical students 12

13. BRONCHIAL TREE
Primary
Secondary
Tertiary
Histology of respiratory system for medical students 13

14. Histology of respiratory system for medical students 14

15. BRONCHIAL TREE
• 1, 2, 3 Bronchi
• Cartilage plates, glands present, smallest is 5mm,
many lymphocytes present
• Bronchioles
• No cartilage, no glands
• Alveolar Duct
• Alveolar Sac
• Gas exchange
• Alveolus
Histology of respiratory system for medical students 15

16. HISTOLOGY OF
BRONCHIAL TREE
• Cartilage
• Rings, plates, disappears
Smooth Muscle Layer
Begins in bronchi,
more prominent in bronchioles
then disappears
• Epithelium
• Pseudostratified, Simple columnar, cuboidal, squamous
Histology of respiratory system for medical students 16

17. Bronchus
Cartilage
Histology of respiratory system for medical students 17

18. Bronchus
Lamina propria
Histology of respiratory system for medical students 18

19. Bronchus
Histology of respiratory system for medical students 19

20. Bronchioles
• > 5mm diameter
• No cartilage or glands in mucosa
• Epithelium changes from
• pseudostratified to cuboidal epithelium.
• shortening along the way.
• Only scattered goblet cells initially.
• Clara cells secrete protective proteins.
• Lamina propria contains only
• smooth muscle and elastic fibers.
• Vagus nerve, sympathetic neurons
Histology of respiratory system for medical students 20

21. Bronchiole x10
Histology of respiratory system for medical students 21

22. Bronchiole x40
Histology of respiratory system for medical students 22

23. Alveolus
Bronchiole
Histology of respiratory system for medical students 23

24. Location of Gas Exchange
Histology of respiratory system for medical students 24

25. ALVEOLUS AND CAPILLARY
Histology of respiratory system for medical students 25

26. GAS EXCHANGE
• Respiratory membrane
• Layers
• Cells present in alveolus
• Simple squamous epithelium
• Other cells in alveolus
• Macrophages
• Surfactant cells
Histology of respiratory system for medical students 26

27. Section of a terminal bronchiole with
a small portion of a respiratory bronchiole
continuous with an alveolar duct and many alveoli. Low magnification.
Histology of respiratory system for medical students 27

28. Histology of respiratory system for medical students 28

29. Diagram of a
portion of the
bronchial tree.
Note that the
smooth muscle in
the alveolar duct
disappears in the
alveoli. (Redrawn
from Baltisberger.)
Histology of respiratory system for medical students 29

30. Transition of a terminal bronchiole into
an alveolar duct (arrow). Note
the Clara cells arrowheads.
Histology of respiratory system for medical students 30

31. Respiratory Duct
With Alveoli
Histology of respiratory system for medical students 31

32. Alveolus
Histology of respiratory system for medical students 32

33. Alveolar Sac
Histology of respiratory system for medical students 33

34. Blood Vessel in Lung
Histology of respiratory system for medical students 34

35. Alveolus with Capillary
Histology of respiratory system for medical students 35

36. Interface
between
capillary
and alveolus
Histology of respiratory system for medical students 36

37. Interface Between Capillary, Alveolus
Histology of respiratory system for medical students 37

38. Alveoli and interalveolar septum
showing capillaries and epithelial
. Cells type I and II
Histology of respiratory system for medical students 38

39. Cells Located in Alveolus
• Type I alveolar cells
• Simple squamous cells
• Type II cells
• Surfactant
• Macrophages (dust cells)
Histology of respiratory system for medical students 39