Respiratory System

• Conduction


  Nasal Cavity --> Terminal bronchioles

  
• Respiratory


  Respiratory Bronchioles --> alveoli

  
• Conducting portion


  • Nasal cavity
  • Nasopharynx
  • Larynx
  • Trachea
  • Primary bronchi (extrapulmonary bronchi)
  • Intrapulmonary bronchi: lobar bronchi, segmental bronchi
  • Primary bronchioles (preterminal bronchioles)
  • Terminal bronchioles

  
• Respiratory portion


  • Respiratory bronchioles
  • Alveolar ducts
  • Alveolar sacs
  • Pulmonary alveoli

  
• Regions of nasal cavity

  • Anterior: Vestibule
  • Posterior: Respiratory region, Olfactory region

  
• Nasal septum


  Divides the nasal cavity into two halves (right and left)

  
• Nasal vestibule


  • Epidermis: Keratinized stratified squamous epithelium
  • Dermis: Vibrissae, Sebaceous glands, Sweat glands
  • Wall: Hyaline cartilage, Cancellous (spongy) bone

  
• Respiratory region of nasal cavity

  • Mucosa (Mucous membrane): Epithelium - Pseudostratified ciliated columnar epithelium with goblet cells (Respiratory epithelium), Lamina propria - Large arterial plexuses, venous sinuses, Many seromucous glands, Abundant lymphoid elements

  
• Paranasal sinuses


  • Lining: 1- Respiratory epithelium, 2- Lamina propria

  
• Sinusitis


  Clinical application
• Olfactory region of nasal cavity


  • Site: Roof of nasal cavity, Upper part of nasal septum, Over superior concha

  Structure: Olfactory epithelium - Pseudostratified columnar epithelium, Olfactory cells, Sustentacular cells, Basal cells

  Lamina propria: Highly vascularized loose to dense CT, Bowman's glands, Bundles of unmyelinated nerve fibers, Rich vascular plexus, Numerous lymphoid elements

  
• Olfactory epithelium


  • Olfactory cells: Bipolar neurons with dendrite having olfactory vesicle with nonmotile cilia, Axons are unmyelinated with Schwann-like cells

  Sustentacular cells: Columnar cells that provide physical support and nourishment for olfactory cells

  
• Larynx


  • Mucosa: Epithelium - Respiratory epithelium, Non keratinized stratified squamous epithelium (on vocal folds and superior surface of epiglottis)

  Lamina propria

  Cartilages: Hyaline cartilages (Thyroid), Elastic cartilages (Epiglottis)

  Skeletal muscles, Ligaments

  
• Vestibular folds


  • Respiratory epithelium, Lamina propria with seromucous glands, lymphoid elements & adipose cells

  
• Vocal folds (cords)


  • Epithelium: Non keratinized stratified squamous, Lamina propria: Elastic fibers and skeletal muscle, No lymphoid nodules/seromucus glands
• Respiratory epithelium


  • Pseudostratified ciliated columnar epithelium with goblet cells

  Main cell types: Ciliated columnar cells, Goblet cells, Basal cells, DNES cells

  
• Trachea


  • Lined with typical respiratory mucosa, Lamina propria contains numerous seromucous glands, C-shaped rings of hyaline cartilage, Trachealis muscle and fibroelastic tissue

  
• Bronchial tree and lung

  Trachea divides into two primary bronchi, Primary bronchi give rise to secondary (lobar) bronchi, Tertiary (segmental) bronchi
• Bronchioles


  • Intralobular airways with diameters of 1 mm or less, Lack mucosal glands and cartilage
• Alveoli


  • Scattered sac-like evaginations, Interalveolar septa with fibroblasts and ECM

  Type I pneumocytes, Type II pneumocytes

  Lung surfactant spread over inner alveolar surface

  
• Blood-air barrier


  Thin type I alveolar cells, Thin capillary endothelial cells, Fused basal laminae allowing gas exchange

  
• Conduction


  Nasal Cavity --> Terminal bronchioles

  
• Respiratory


  Respiratory Bronchioles --> alveoli

  
• Conducting portion


  • Nasal cavity
  • Nasopharynx
  • Larynx
  • Trachea
  • Primary bronchi (extrapulmonary bronchi)
  • Intrapulmonary bronchi: lobar bronchi, segmental bronchi
  • Primary bronchioles (preterminal bronchioles)
  • Terminal bronchioles

  
• Respiratory portion


  • Respiratory bronchioles
  • Alveolar ducts
  • Alveolar sacs
  • Pulmonary alveoli

  
• Regions of nasal cavity

  • Anterior: Vestibule
  • Posterior: Respiratory region, Olfactory region

  
• Nasal septum


  Divides the nasal cavity into two halves (right and left)

  
• Nasal vestibule


  • Epidermis: Keratinized stratified squamous epithelium
  • Dermis: Vibrissae, Sebaceous glands, Sweat glands
  • Wall: Hyaline cartilage, Cancellous (spongy) bone

  
• Respiratory region of nasal cavity

  • Mucosa (Mucous membrane): Epithelium - Pseudostratified ciliated columnar epithelium with goblet cells (Respiratory epithelium), Lamina propria - Large arterial plexuses, venous sinuses, Many seromucous glands, Abundant lymphoid elements

  
• Paranasal sinuses


  • Lining: 1- Respiratory epithelium, 2- Lamina propria

  
• Sinusitis


  Clinical application
• Olfactory region of nasal cavity


  • Site: Roof of nasal cavity, Upper part of nasal septum, Over superior concha

  Structure: Olfactory epithelium - Pseudostratified columnar epithelium, Olfactory cells, Sustentacular cells, Basal cells

  Lamina propria: Highly vascularized loose to dense CT, Bowman's glands, Bundles of unmyelinated nerve fibers, Rich vascular plexus, Numerous lymphoid elements

  
• Olfactory epithelium


  • Olfactory cells: Bipolar neurons with dendrite having olfactory vesicle with nonmotile cilia, Axons are unmyelinated with Schwann-like cells

  Sustentacular cells: Columnar cells that provide physical support and nourishment for olfactory cells

  
• Larynx


  • Mucosa: Epithelium - Respiratory epithelium, Non keratinized stratified squamous epithelium (on vocal folds and superior surface of epiglottis)

  Lamina propria

  Cartilages: Hyaline cartilages (Thyroid), Elastic cartilages (Epiglottis)

  Skeletal muscles, Ligaments

  
• Vestibular folds


  • Respiratory epithelium, Lamina propria with seromucous glands, lymphoid elements & adipose cells

  
• Vocal folds (cords)


  • Epithelium: Non keratinized stratified squamous, Lamina propria: Elastic fibers and skeletal muscle, No lymphoid nodules/seromucus glands
• Respiratory epithelium


  • Pseudostratified ciliated columnar epithelium with goblet cells

  Main cell types: Ciliated columnar cells, Goblet cells, Basal cells, DNES cells

  
• Trachea


  • Lined with respiratory mucosa, Lamina propria with numerous seromucous glands, C-shaped rings of hyaline cartilage, Trachealis muscle, Fibroelastic tissue

  
• Bronchial tree and lung

  Trachea divides into two primary bronchi, Primary bronchi give rise to secondary (lobar) bronchi, Tertiary (segmental) bronchi
• Bronchioles


  • Intralobular airways with diameters of 1 mm or less, Lack mucosal glands and cartilage