respiratory system

• Respiratory system

  Protects against various microorganisms, has parts involved in immune defense and homeostasis
• Primary function of respiratory system

  • Provides for exchange of O2 and CO2 to and from the blood
• Respiratory system


  • Lungs and a branching system of bronchial tubes that link the sites of gas exchange with the external environment
• Secondary function of respiratory system

  • Maintenance of homeostasis
  • Maintenance of acid base
• Division of respiratory system

  • Conducting portion
  • Respiratory portion

  
• Conducting portion

  Transportation of gases
• Upper conducting portion

  • Nasal cavities
  • Nasopharynx
  • Larynx
• Lower conducting portion

  • Trachea
  • Extrapulmonary bronchi
  • Intrapulmonary bronchi
  • Bronchioles
  • Terminal bronchioles
• Respiratory portion


  Where the system's main function of gas exchange occurs, consisting of: respiratory bronchioles, alveolar ducts, alveoli
• Conducting portion function

  • To provide conduit through which air moves to and from the lungs
  • To condition the inspired air and ensure uninterrupted supply of air
• Composition of conducting portion

  • Cartilages (both elastic cartilages), collagen fibers, smooth muscle (provide structure of support, testability)
• Upper respiratory conducting portion

  • Nasal cavity
  • Nasopharynx
  • Oropharynx
  • Larynx

  
• Upper respiratory conducting portion lining

  • Pseudostratified ciliated columnar epithelium (respiratory epithelium)

  
• Cell types in conducting portion

  • Ciliated columnar cells
  • Goblet cells
  • Brush cells
  • Small granule cells (Kulchitsky cell)
  • Basal cells
• Ciliated columnar cells


  Most abundant with about 300 cilia on apical surface
• Goblet cells

  Filled with granules of mucin glycoproteins
• Brush cells

  Columnar cell type with blunt microvilli and chemosensory receptors (sense of smell)
• Small granule cells (Kulchitsky cell)


  Difficult to distinguish but possess numerous dense core granules 100-300 mm in diameter (contain hormone which help the function of secretory cells), part of neuroendocrine system
• Basal cells

  Small, rounded cells on the basement membrane that do not extend to the luminal surface, stem cells that give rise to other cell types
• Lower respiratory airway

  • Trachea
  • Bronchi
  • Bronchioles
  • Terminal bronchioles

  
• Each portion of the lower respiratory airway has unique tissue components, which facilitate oxygen delivery, gas exchange, and immune defense mechanisms

  
• Individual airways decrease in diameter as they continue branching
• Regions of nasal cavity

  • Nasal vestibule
  • Nasal mucosa
  • Olfactory mucosa
• Nasal vestibule


  First portion of upper respiratory tract, covered by keratinized stratified squamous epithelium and vibrissae (stiff hairs)

  
• Nasal mucosa

  Covered by pseudostratified ciliated epithelium (respiratory epithelium) which contain ciliated columnar cells, goblet cells, basal cells, and neuroendocrine cells

  
• Nasal mucosa function

  Filters, warms and moisturises the inhaled air
• Olfactory mucosa


  Located in the roof of the nasal cavity, covered by pseudostratified columnar epithelium (composed of ciliated olfactory cells, non-ciliated columnar cells and basal cells), site for odorant chemoreception

  
• Regions of pharynx

  • Nasopharynx
  • Oropharynx
  • Laryngopharynx
• Layers of pharynx

  • Mucosa
  • Submucosa
  • Muscularis
  • Adventitia
• Nasopharynx and oropharynx

  Both conduct air from the nasal cavity and oral cavity to the larynx, oropharynx is lined by stratified squamous epithelium, nasopharynx is lined by respiratory epithelium

  
• Pharynx

  It conducts warm and moist filtered air because of the hair from the nasal cavity to the larynx
• The Pharynx is divided into three

  Nasopharynx, Oropharynx and the Laryngopharynx
• Larynx It contains epiglottis and the vocal chords. It is covered in respiratory epithelium
• True Vocal chords is covered by Non-keratinized stratified squamous and numerous elastic fibers
• Trachea, Bronchi, Bronchioles, and terminal bronchi has a unique tissue component that will facilitate delivery of oxygen and facilitate gas exchange and gets smaller in diameter as it branches continously
• Trachea is a C-shaped cartilage w/about 10-12 Hyaline cartilage rings bridged with Trachealis Muscle. It is lined with respiratory epithelium
• What are the layers of the Trachea?

  Mucosa, Submucosa, Cartilage Layer, and adventitia
• Bronchus: any of the major air passages of the lungs which diverge from the windpipe. Consist of the left and right bronchi
• Primary Bronchi is lined with respiratory epithelium and have C-shaped hyaline cartilage. Similar to trachea
• Right Bronchus gives rise to 3 branches and that is the Secondary Bronchi