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

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

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

Epithelium in the respiratory system

Epithelium in the respiratory system

Epithelium in the respiratory system

Epithelium in the respiratory system Olfactory epithelium Respiratory epithelium

Epithelium in the respiratory system Skin junction

Ut 429 False vocal cords True vocal cords 38b

Respiratory epithelium of trachea Basement membrane Ciliated cell Goblet cell

EM 8 trachea; 20630x Mucous Microvilli Cilia Goblet cell

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.

Respiratory epithelium 36

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

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

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

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

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

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

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

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.

38b false true CRICOID cartilage THYROID cartilage

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

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

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

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.

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

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

bronchus bronchus

Bronchial tree Copyright McGraw-Hill Companies

Cells in the respiratory portion 41 TERMINAL BRONCHIOLE CLARE CELLS 259 Smooth muscle Smooth muscle Ciliated cells Elastic fibers Respiratory BRONCHIOLE

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

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

Capillaries

Capillaries

BLOOD-AIR BARRIER SURFACE LINING AND CYTOPLASM OF ALVEOLAR CELLS 42 BLOOD-AIR BARRIER SURFACE LINING AND CYTOPLASM OF ALVEOLAR CELLS FUSED BASAL LAMINAE CYTOPLASM OF ENDOTHELIAL CELL

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.

36721

19714 lung macrophages macrophages

432 macrophages macrophages

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.

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

MACROPHAGES

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

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.

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

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.

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

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

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

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)

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

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

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.

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. 1983. Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY. Bruce Alberts, et al. 1994. Molecular Biology of the Cell. Garland Publishing, Inc., New York, NY. William J. Banks, 1981. Applied Veterinary Histology. Williams and Wilkins, Los Angeles, CA. Hans Elias, et al. 1978. Histology and Human Microanatomy. John Wiley and Sons, New York, NY. Don W. Fawcett. 1986. Bloom and Fawcett. A textbook of histology. W. B. Saunders Company, Philadelphia, PA. Don W. Fawcett. 1994. Bloom and Fawcett. A textbook of histology. Chapman and Hall, New York, NY. Arthur W. Ham and David H. Cormack. 1979. Histology. J. S. Lippincott Company, Philadelphia, PA. Luis C. Junqueira, et al. 1983. Basic Histology. Lange Medical Publications, Los Altos, CA. L. Carlos Junqueira, et al. 1995. Basic Histology. Appleton and Lange, Norwalk, CT. L.L. Langley, et al. 1974. Dynamic Anatomy and Physiology. McGraw-Hill Book Company, New York, NY. W.W. Tuttle and Byron A. Schottelius. 1969. Textbook of Physiology. The C. V. Mosby Company, St. Louis, MO. Leon Weiss. 1977. Histology Cell and Tissue Biology. Elsevier Biomedical, New York, NY. Leon Weiss and Roy O. Greep. 1977. Histology. McGraw-Hill Book Company, New York, NY. Nature (http://www.nature.com), Vol. 414:88,2001. A.L. Mescher 2013 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

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