1. Dr. Larry Johnson Texas A&M University
Respiratory system 42
Dr. Larry Johnson Texas A&M University

2. Objectives Characterize each subdivision of the respiratory
system (larynx, trachea, bronchus, bronchioles, alveolar ducts, alveoli).
Identify each of the cell types and matrix components that are involved with respiratory conduction and conditioning of the inspired air.
Describe the structure and function of each of the components of the alveolar septum including alveolar macrophages, Type I and II alveolar cells, capillaries, fibroblasts, mast cells and matrix fibers (collagen III and elastin).
Identify the air passages found in the lungs. These include the respiratory bronchioles, alveolar ducts, and alveoli. 36
36b 42

3. Respiratory System Conduction Respiration Structure
Maintenance of an open lumen
Ability to accommodate expansion and contraction,
Warming, moisturizing and filtering of the inspired air
Respiration
Rapid exchange of atmospheric gases
Alveolar wall cells secrete surfactant
Structure
Skeletal components (cartilage, etc.)
Vascularization
Glands in lamina propria
Copyright McGraw-Hill Companies

4. Epithelium in the respiratory system

5. Epithelium in the respiratory system

6. Epithelium in the respiratory system

7. Epithelium in the respiratory system
Olfactory
epithelium
Respiratory
epithelium

8. Epithelium in the respiratory system
Skin junction

9. Ut 429
False vocal cords
True vocal cords
38b

10. Respiratory epithelium of trachea
Basement membrane
Ciliated cell
Goblet cell

11. EM 8 trachea; 20630x
Mucous
Microvilli
Cilia
Goblet cell

15. 36
The highly vascular nature of the lamina propria is important for conditioning inhaled air. A complex vasculature with loops of capillaries near the epithelial surface carries blood in a general direction counter to the flow of inspired air and releases heat to warm that air. Also, the swell bodies reduce the flow of air on either side of the nose and switches every 30 min to allow rehydration on one side as air flow is shifted to the other side.

16. Respiratory epithelium36

17. Slide 36: Respiratory (Olfactory) mucosa and nasal septum
What type of cartilage is the nasal septum?
Hyaline cartilage
What is the significance of the highly vascular nature of the lamina propria?
The highly vascular nature of the lamina propria is important for conditioning inhaled air. A complex vasculature with loops of capillaries near the epithelial surface carries blood in a general direction counter to the flow of inspired air and releases heat to warm that air.
Highly vascular lamina propria
Swell bodies
Cartilaginous nasal septum
Bowman’s glands
Pseudostratified columnar epithelium
Hyaline cartilage

21. Slide 36: Respiratory (Olfactory) mucosa and nasal septum
Highly vascular lamina propria
Swell bodies
What type of cartilage is the nasal septum?
Hyaline cartilage
What is the significance of the highly vascular nature of the lamina propria?
The highly vascular nature of the lamina propria is important for conditioning inhaled air. A complex vasculature with loops of capillaries near the epithelial surface carries blood in a general direction counter to the flow of inspired air and releases heat to warm that air.
Olfactory
epithelium
Bowman’s
glands

22. Slide 36 001: Respiratory (Olfactory) mucosa and nasal septum
Highly vascular lamina propria
Swell bodies
What type of cartilage is the nasal septum?
Hyaline cartilage
What is the significance of the highly vascular nature of the lamina propria?
The highly vascular nature of the lamina propria is important for conditioning inhaled air. A complex vasculature with loops of capillaries near the epithelial surface carries blood in a general direction counter to the flow of inspired air and releases heat to warm that air.
Olfactory
epithelium
Bowman’s
glands
Nerves

23. Slide 36: Respiratory (Olfactory) mucosa and nasal septum
What type of cartilage is the nasal septum?
Hyaline cartilage
What is the significance of the highly vascular nature of the lamina propria?
The highly vascular nature of the lamina propria is important for conditioning inhaled air. A complex vasculature with loops of capillaries near the epithelial surface carries blood in a general direction counter to the flow of inspired air and releases heat to warm that air.
Respiratory mucosa
Olfactory mucosa
Bowman’s glands
Swell bodies

24. LARYNX - IRREGULAR TUBE CONNECTS PHARYNX TO TRACHEA
CARTILAGE
LARGE - HYALINE - THYROID, CRICOID
SMALLER - ELASTIC - EPIGLOTTIS

25. Slide 37: Epiglottis Lamina propria with mucous glands
Nonkeratinized stratified squamous lingual epithelium
Elastic cartilage
3. How are they different and how does their appearance reflect their anatomical position?
Superior (lingual) surface: nonkeratinized stratified squamous epithelium; when the epiglottis is covering the larynx, this layer is exposed and acts as a barrier to prevent swallowed food or fluid from entering the larynx
Inferior (laryngeal) surface: pseudostratified columnar respiratory epithelium; this layer is exposed during breathing, when the epiglottis is not covering the larynx, and acts as respiratory epithelium
Respiratory epithelium
Respiratory
epithelium

26. Superior (lingual) surface: nonkeratinized stratified squamous epithelium; when the epiglottis is covering the larynx, this layer is exposed and acts as a barrier to prevent swallowed food or fluid from entering the larynx
Inferior (laryngeal) surface: pseudostratified columnar respiratory epithelium; this layer is exposed during breathing, when the epiglottis is not covering the larynx, and acts as respiratory epithelium

27. 429 larynx
Two types of cartilage are found in the larynx. Elastic cartilage occurs only in the epiglottis of the larynx. All other cartilage in the respiratory system is hyaline.

28. 38b
false
true
CRICOID cartilage
THYROID cartilage

29. Slide 38: Larynx
False vocal cord with laryngeal glands
Tracheal hyaline cartilage
Vocalis muscle and vocal ligament of true vocal cord
4. What two types of cartilage are found in the larynx?
1. Elastic cartilage of epiglottis
2. Hyaline cartilage of trachea
False vocal cord
True vocal cord
True vocal cord nonkeratinized stratified squamous epithelium
False vocal cord pseudostratified ciliated columnar epithelium
Laryngeal ventricle

30. Slide 39: Lower Larynx (trichrome)6 7 2 2 1 3 3 4 4 1 2 2 5 2
5. Which specific cartilage is this (lower larynx)?
Hyaline cartilage 2 3 1
Psuedostratified ciliated columnar respiratory epithelium
1. Thyroid
5. Respiratory epithelium
Lymphoid nodules
Glands
Hyaline cartilage
2. Skeletal muscle
6. Esophagus
3. Hyaline cartilage
7. Brown fat
4. Connective tissue

31. TRACHEA THIN WALLED TUBE 16-20 C-SHAPED RINGS OF HYALINE
TRACHEALIS MUSCLE
SMOOTH MUSCLE
ALLOWS FOR REGULATION OF SIZE OF LUMEN FOR COUGH REFLEX

32. Trachea, monkey – glands in trachea
The capacity to narrow the lumen of the trachea by contraction of the trachealis muscle is important in the cough reflex . Narrowing the tracheal lumen increases the velocity of the expelled air and better loosening of material in the air passage.

39. Slide 40: Trachea Pseudostratified ciliated columnar epithelium
6. Why would you want to narrow the lumen of the trachea?
The trachealis muscle contracts in the cough reflex to narrow the tracheal lumen and provide for increased velocity of the expelled air and better loosening of material in the air passage.
Pseudostratified ciliated columnar epithelium
Lamina propria composed of loose CT
Trachealis muscle
Gland in submucosa
Hyaline cartilage

40. Slide 40: Trachea Goblet cells Large nerve Blood vessel Lymph nodule
6. Why would you want to narrow the lumen of the trachea?
The trachealis muscle contracts in the cough reflex to narrow the tracheal lumen and provide for increased velocity of the expelled air and better loosening of material in the air passage.
Blood vessel
Lymph nodule

41. bronchus
bronchus

42. Bronchial tree
Copyright McGraw-Hill Companies

44. Cells in the respiratory portion41
TERMINAL BRONCHIOLE
CLARE CELLS
259
Smooth
muscle
Smooth
muscle
Ciliated cells
Elastic fibers
Respiratory BRONCHIOLE

45. Cells in the respiratory portion
BRONCHIOLE
Type I cells
Endothelium
Type II
cells
Macrophages 41

46. Slide 41: Lung Conducting bronchiole Respiratory bronchioles Bronchus
7. What is the function of alveolar macrophages? Why are these cells sometimes referred to as heart failure cells?
Alveolar macrophages phagocytize erythrocytes lost from damaged capillaries and airborne particulate matter that has penetrated as gar as the alveoli.
In congestive heart failure, the lungs become congested with blood, and erythrocytes pass into the alveoli, where they are phagocytized by alveolar macrophages. In such cases, these macrophages are called heart failure cells.
Alveoli
Alveolar duct
Alveolar sac

47. Capillaries

48. Capillaries

49. BLOOD-AIR BARRIER SURFACE LINING AND CYTOPLASM OF ALVEOLAR CELLS42
BLOOD-AIR BARRIER
SURFACE LINING AND CYTOPLASM OF ALVEOLAR CELLS
FUSED BASAL LAMINAE
CYTOPLASM OF ENDOTHELIAL CELL

51. 48
36721
Mast cells function in the localized release of many bioactive substances with roles in the local inflammatory response, innate immunity, and tissue repair.
Mast cell granules normally contain: heparin, histamine, serine proteases, eosinophil and neutrophil chemotactic factors, cytokines, etc.

52. 36721

53. 19714 lung macrophages
macrophages

54. 432
macrophages
macrophages

55. Type I pneumonocyte
Type II pneumonocyte
Type II pneumocytes produce surfactant which helps prevent alveolar collapse at exhalation by reducing surface tension and allows alveoli to be inflated with less respiratory force, easing the work of breathing.

56. Slide 41 and 42: Lung 42 42 42 41 Mesothelium and connective tissue
Type I & Type II pneumocytes
7. What is the function of alveolar macrophages? Why are these cells sometimes referred to as heart failure cells?
Alveolar macrophages phagocytize erythrocytes lost from damaged capillaries and airborne particulate matter that has penetrated as gar as the alveoli.
In congestive heart failure, the lungs become congested with blood, and erythrocytes pass into the alveoli, where they are phagocytized by alveolar macrophages. In such cases, these macrophages are called heart failure cells. 42 41
Capillary endothelial cells and fibroblasts
Alveolar macrophage

57. MACROPHAGES

58. Slide 42 : Lung (mast cells)
Bronchus
19714
Conducting bronchiole
Mesothelium
8. What is the function of mast cells? Name a compound normally found in mast cell granules?
Mast cells function in the localized release of many bioactive substances with roles in the local inflammatory response, innate immunity, and tissue repair.
Mast cell granules normally contain: heparin, histamine, serine proteases, eosinophil and neutrophil chemotactic factors, cytokines, etc.
9. What respiratory cell releases surfactant?
Type II pneumocytes produce surfactant which helps prevent alveolar collapse at exhalation and allows alveoli to be inflated with less respiratory force, easing the work of breathing.
10 What respiratory cell is the primary contributor to the alveolar lining?
Type I pneumocytes cover about 95% of the alveolar surface.
Respiratory bronchiole
Alveolar duct
Alveolar sac
Type I pneumocyte
Alveolar
macrophage
Type II pneumocyte
Alveoli

59. 19714 lung
Alveolar macrophages phagocytize erythrocytes lost from damaged capillaries and airborne particulate matter that has penetrated as gar as the alveoli.
In congestive heart failure, the lungs become congested with blood, and erythrocytes pass into the alveoli, where they are phagocytized by alveolar macrophages. In such cases, these macrophages are called heart failure cells.

62. Small pieces of lungs from a non-smoker
and from a smoker

64. EM 22 & 23
8. What is the function of mast cells? Name a compound normally found in mast cell granules?
Mast cells function in the localized release of many bioactive substances with roles in the local inflammatory response, innate immunity, and tissue repair.
Mast cell granules normally contain: heparin, histamine, serine proteases, eosinophil and neutrophil chemotactic factors, cytokines, etc.
9. What respiratory cell releases surfactant?
Type II pneumocytes produce surfactant which helps prevent alveolar collapse at exhalation and allows alveoli to be inflated with less respiratory force, easing the work of breathing.
10 What respiratory cell is the primary contributor to the alveolar lining?
Type I pneumocytes cover about 95% of the alveolar surface.

65. Type I pneumocytes cover about 95% of the alveolar surface as this cell is primary contributor to the alveolar lining.

71. RESPIRATORY PHYSIOLOGY
SURFACTANT FUNCTIONS IN REDUCING SURFACE TENSION, REDUCES WORK OF BREATHING, AND HELPS KEEP ALVEOLI OPEN AND MAY HAVE A BACTERICIDAL EFFECT

72. RESPIRATORY PHYSIOLOGY
SURFACTANT FUNCTIONS IN REDUCING SURFACE TENSION, REDUCES WORK OF BREATHING, AND HELPS KEEP ALVEOLI OPEN AND MAY HAVE A BACTERICIDAL EFFECT
HYALINE MEMBRANE DISEASE - PREMATURE INFANTS CANNOT GET OR MAKE SUFFICIENT SURFACTANT

73. RESPIRATORY PHYSIOLOGY
SURFACTANT FUNCTIONS IN REDUCING SURFACE TENSION, REDUCES WORK OF BREATHING, AND HELPS KEEP ALVEOLI OPEN AND MAY HAVE A BACTERICIDAL EFFECT
HYALINE MEMBRANE DISEASE - PREMATURE INFANTS CANNOT GET OR MAKE SUFFICIENT SURFACTANT
BRONCHOALVEOLAR FLUID - CLEARED BY CILIARY ACTION TOWARD ORAL CAVITY (CONTAIN LYSOSOME, COLLAGENASE, GLUCURONIDASE)

74. RESPIRATORY PHYSIOLOGY
SURFACTANT FUNCTIONS IN REDUCING SURFACE TENSION, REDUCES WORK OF BREATHING, AND HELPS KEEP ALVEOLI OPEN AND MAY HAVE A BACTERICIDAL EFFECT
HYALINE MEMBRANE DISEASE - PREMATURE INFANTS CANNOT GET OR MAKE SUFFICIENT SURFACTANT
BRONCHOALVEOLAR FLUID - CLEARED BY CILIARY ACTION TOWARD ORAL CAVITY (CONTAIN LYSOSOME, COLLAGENASE, GLUCURONIDASE)
MACROPHAGES - CONTAIN HEMOSIDERIN, PRODUCE LYTIC ENZYMES IN BRONCHOALVEOLAR FLUID

75. Clinical Correlation
A patient has been smoking for 30 years. He develops a hoarse voice and, upon examination, the larynx is inflamed. The patients larynx may now contain nonkeratinized stratified squamous epithelium. This change in epithelial state is termed metaplasia Because of his excessive smoking, this patient has also developed emphysema.
10. What type of epithelium might be found in this patient’s larynx? This change in epithelial state is termed ___________.
Nonkeratinized stratified squamous epithelium
Metaplasia
11. Describe the histologic differences observed in a lung biopsy from this patient as compared to a lung from a normal patient. (Text p. 314)
Emphysema involves dilation and permanent enlargement of the bronchioles leading to pulmonary acini and accompanying loss of cells in the alveoli and other parts of the airway walls, leading to irreversible loss or respiratory function.
Edward C. Klatt, M.D.
Mercer University School of Medicine
Normal larynx with ciliated pseudostratified columnar epithelium
Abnormal larynx with stratified squamous epithelium

78. Respiratory Diseases
Emphysema (means too much air in the lungs due to loss of alevolar walls) involves dilation and permanent enlargement of the bronchioles leading to pulmonary acini and accompanying loss of cells in the alveoli and other parts of the airway walls, leading to irreversible loss or respiratory function.
Many infectious agents attack the respiratory tract.
The most common respiratory disease is the cold, but others include bronchitis, influenza, SARS, and pneumonia.
Knowledge
An exercise: ask students what they think the most likely routes of infection are for respiratory infections. Answers should include the nose and breathing contaminated air.

79. Many illustrations in these VIBS Histology YouTube videos were modified from the following books and sources: Many thanks to original sources!
Bruce Alberts, et al Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY.
Bruce Alberts, et al Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY.
William J. Banks, Applied Veterinary Histology. Williams and Wilkins, Los Angeles, CA.
Hans Elias, et al Histology and Human Microanatomy. John Wiley and Sons, New York, NY.
Don W. Fawcett Bloom and Fawcett. A textbook of histology. W. B. Saunders Company, Philadelphia, PA.
Don W. Fawcett Bloom and Fawcett. A textbook of histology. Chapman and Hall, New York, NY.
Arthur W. Ham and David H. Cormack Histology. J. S. Lippincott Company, Philadelphia, PA.
Luis C. Junqueira, et al Basic Histology. Lange Medical Publications, Los Altos, CA.
L. Carlos Junqueira, et al Basic Histology. Appleton and Lange, Norwalk, CT.
L.L. Langley, et al Dynamic Anatomy and Physiology. McGraw-Hill Book Company, New York, NY.
W.W. Tuttle and Byron A. Schottelius Textbook of Physiology. The C. V. Mosby Company, St. Louis, MO.
Leon Weiss Histology Cell and Tissue Biology. Elsevier Biomedical, New York, NY.
Leon Weiss and Roy O. Greep Histology. McGraw-Hill Book Company, New York, NY.
Nature ( Vol. 414:88,2001.
A.L. Mescher Junqueira’s Basis Histology text and atlas, 13th ed. McGraw
Douglas P. Dohrman and TAMHSC Faculty 2012 Structure and Function of Human Organ Systems, Histology Laboratory Manual - Slide selections were largely based on this manual for first year medical students at TAMHSC

80. The End!