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Dr. Sama ul Haque
Dr. Safaa
Histology of Respiratory Tract
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 portionConducting portion1.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 CavityRespiratory segment
- Respiratory Epithelium
- Lamina Propria
Olfactory segment
- Olfactory Epithelium:
i. Olfactory cells (bipolar neurons)
ii. Basal cells
iii. Supportive cells
- Lamina Propria
Nasal Cavity
Lamina Propria
Mucous GlandsSerous GlandsVenous SinusesMucoperiosteum or Mucoperichondrium
Secretions of nasal mucosa- Bactericides - Lysozymes
Olfactory Epithelium
Nasopharynx
MucosaRespiratory EpitheliumStratified Squamous Epithelium
Lamina PropriaElastic TissueMucus Gland
Larynx
MucosaFalse vocal cords: Pseudostratified ciliated
columnar epithelium True vocal cords: Non Keratinized stratified
squamous epitheliumIntrinsic MusclesCartilages
- Larger Laryngeal Cartilages (Hyaline)
Larynx
Epiglottis
MucosaAnteriorly (Lingual mucosa):
Non Keratinized stratified squamous epithelium
Posteriorly: (Laryngeal mucosa):Pseudostratified ciliated columnar epithelium
Elastic Cartilage
Epiglottis
Trachea Mucosa
Pseudostratified ciliated columnar epithelium Lamina propia
Sub mucosa Connective Tissue Seromucous bronchial Glands
Hyaline Cartilage
Adventitia
Trachea
Trachea
Lung
BronchiMucosa;
Pseudostratified ciliated columnar epithelium Lamina propia
Muscularis; Submucosa;
Connective Tissue Seromucous Glands
Cartilage layer; Adventitia. Connective Tissue
At 1 mm diameter, the cartilage plates disappear and it becomes a bronchiole.
Respiratory Bronchioles
Alveolar Ducts
And
Alveoli
Intrapulmonary Bronchus
Terminal Bronchiole
Respiratory Bronchiole
Simple cuboidal epithelium
Alveolar CellsAlveolar Epithelial Cells (Type I Pneumocyte)Type II PneumocyteInteralveolar Pores Alveolar Macrophages (dust cells)Alveolar Surfactant
Alveolar walls & Alveolar cells
Alveolar walls & Alveolar cells
Respiratory Membrane It is the area where gas exchange occurs. It is formed of:
Alveolar Epithelium.
Fused basement membranes of the alveolar epithelium and the capillary endothelium.
Capillary Endothelium.
Thank you