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Histology of Respiratory Tract. Dr. Sama ul Haque Dr . Safaa. Objectives. Differentiate between the olfactory and nasal mucosa. Discuss the microscopic structure of larynx. Describe the microscopic structure of trachea and lungs.
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Histology of Respiratory Tract Dr. SamaulHaque Dr. Safaa
Objectives • Differentiate between the olfactory and nasal mucosa. • Discuss the microscopic structure of larynx. • Describe the microscopic structure of trachea and lungs. • Differentiate between the terminal and respiratory bronchioles. • Explain alveolar cells.
Respiratory System • This consists of the lungs and the air passages that lead to and form the lungs. • The air passages branch as they enter the lungs to finally form alveoli. • This system has 3 functions: 1.Air conduction; 2.Air filtration; 3.Gas exchange (respiration).
Air passages consist of: • A conducting portion • A respiratory portion • 1.Nasal cavities; 2.Nasopharynx and oropharynx; 3.Larynx; 4.Trachea; 5.Paired primary bronchi. Bronchi within the lungs branch extensively to form bronchioles. The terminal bronchioles form the last part of the conducting system.
The respiratory portion is the part of the tract where gaseous exchange takes place and includes: 1.Respiratory bronchioles; 2.Alveolar ducts; 3.Alveolar sacs; 4.Alveoli.
Respiratory Epithelium • The typical respiratory epithelium consists of 5 cell types: 1.Ciliated cells; 2.Goblet cells; 3.Brush cells (have short blunt microvilli); 4.Small granule cells (contain secretory granules); 5.Basal cells (stem cells).
Nasal Cavity • Keratinized stratified squamous epithelium • Non Keratinized stratified squamous epithelium • Pseudostratified ciliated columnar epithelium with goblet cells • Olfactory Epithelium
Nasal Cavity • Nasal Cavity formed of: • 1.Vestibule. 2.Respiratory segment. 3.Olfactory segment • Vestibule: Keratinized stratified squamous epithelium Non Keratinized stratified squamous Contains vibrissae (fine hair), sebaceous glands and sweat glands
Nasal Cavity • Resp to olfepith transition zone-str column epth with cilia and goblet cells to str column epit. Without cilia and with olf cells… • Respiratory segment - Respiratory Epithelium - Lamina Propria • Olfactory segment - Olfactory Epithelium: i. Olfactory cells (bipolar neurons) ii. Basal cells iii. Supportive cells - Lamina Propria
Lamina Propria • Mucous Glands • Serous Glands • Venous Sinuses • Mucoperiosteum or Mucoperichondrium • Secretions of nasal mucosa - Bactericides - Lysozymes
Nasopharynx Mucosa • Respiratory Epithelium • Stratified Squamous Epithelium Lamina Propria • Elastic Tissue • Mucus Gland
Larynx • Mucosa False vocal cords: Pseudostratified ciliated columnar epithelium True vocal cords: Non Keratinized stratified squamous epithelium • Intrinsic Muscles • Cartilages - Larger Laryngeal Cartilages (Hyaline)