Respiratory System

• The respiratory system is important for the process of breathing or the inhalation of oxygen and the release of toxic wastes in the form of Carbon Dioxide
• Portions of the respiratory system


  • Conducting Portion
  • Respiratory Portion
• Conducting Portion


  Components that will condition the air and bring that air into the lungs
• Components of the Conducting Portion


  • Nasal cavities
  • nasopharynx
  • larynx
  • trachea
  • bronchi
  • bronchioles
  • terminal bronchioles
• Respiratory Portion


  Where the actual gas exchange occurs
• Components of the Respiratory Portion


  • Respiratory bronchioles
  • Alveolar ducts
  • alveoli
• Nasal cavity


  • Paired chambers separated by a bony and cartilaginous septum
  • Divided into three regions: nasal vestibule, respiratory region, olfactory region
• Olfactory mucosa


  Composed of olfactory epithelium specialized for olfaction or the sense of "smell"
• Nasal vestibule


  Dilated space of the nasal cavity just inside the nostrils and lined by skin
• Respiratory region


  Largest part of the nasal cavities and lined by respiratory mucosa
• Olfactory region


  Located at the apex of each nasal cavity and lined by specialized olfactory mucosa
• Olfactory epithelium

  • Olfactory chemoreceptors for the sense of smell
  • Pseudostratified columnar epithelium with three major cell types: olfactory neurons, supporting cells, basal cells
• Olfactory neurons


  Bipolar neurons that span the thickness of the epithelium and act as membrane chemoreceptors
• Supporting cells


  Columnar, with broad, cylindrical apexes that help maintain a microenvironment conducive to olfactory function and survival
• Basal cells


  Small, spherical or cone-shaped cells near the basal lamina that act as a stem cell or progenitor cell for the two other types of cell in the olfactory epithelium
• Olfactory glands


  Large serous glands which produce a constant flow of fluid surrounding the olfactory cilia and facilitating the access of new odoriferous substances
• Nasopharynx


  Serves as a passageway for air and food and acts as a resonating chamber for speech
• Larynx


  Passage for air between the pharynx and the trachea, complex tubular region of the respiratory system formed by irregularly shaped plates of hyaline and elastic cartilage, organ for producing sounds
• Structures of the larynx


  • Vocal folds
  • Ventricles
  • Ventricular folds
  • Epiglottis
• Vocal folds


  Control the flow of air through the larynx and vibrate to produce sound, covered with stratified squamous epithelium, supported by dense regular bundle of elastic connective tissue (vocal ligament), with large bundles of striated fibers that comprise the vocalis muscle
• Ventricles


  Elongated recesses in the larynx above the vocal folds
• Ventricular folds


  "False vocal cords" that do not have muscular movement and do not modulate intonation but play an important role in vocal resonance
• Epiglottis


  Flattened structure projecting from the upper rim of the larynx that serves to prevent swallowed food or fluid from entering the passage
• Trachea


  Lined with typical respiratory mucosa, lamina propria contains numerous seromucous glands producing watery mucus, reinforced by a dozen C-shaped rings of hyaline cartilage in the submucosa, with the open ends bridged by the trachealis muscle
• Divisions of the bronchial tree


  • Primary bronchi
  • Secondary bronchi
  • Tertiary bronchi
  • Smaller bronchi
  • Bronchioles
  • Segmental bronchi
  • Lobar bronchi
• Bronchi


  • Lined with respiratory epithelium, folded appearance due to contraction of smooth muscle, plates of hyaline cartilage (not C-shaped), abundant small mucous and serous glands in the submucosa
• The trachea is lined by typical respiratory epithelium underlain by connective tissue of the lamina propria and seromucous glands in the lamina propria and submucosa, with C-shaped rings of hyaline cartilage in the submucosa
• The epithelial lining of bronchi is mainly pseudostratified ciliated columnar cells with a few goblet cells, with a distinct layer of smooth muscle surrounding the entire bronchus
• Bronchial tree


  • Wall surrounded by hyaline cartilage
  • Contains seromucous glands in submucosa
• Trachea


  • Lined by respiratory epithelium
  • Underlain by connective tissue of lamina propria
  • Contains seromucous glands in lamina propria and submucosa
  • Submucosa contains C-shaped rings of hyaline cartilage covered by perichondrium
• Bronchi


  • Epithelial lining is pseudostratified ciliated columnar cells with goblet cells
  • Lamina propria contains distinct layer of smooth muscle
  • Submucosa is site of supporting cartilage
  • Adventitia includes blood vessels and nerves
  • Surrounded by lung tissue
• Bronchioles lack supporting cartilage and glands
• Large bronchiole


  • Characteristically folded respiratory epithelium
  • Prominent smooth muscle
• Smaller bronchiole


  • Epithelium is simple columnar but still ciliated
  • High elastic content of smooth muscle
  • Connective tissue includes lymphocytes of diffuse MALT and lymphoid nodules
• Very small bronchioles


  • Epithelium is simple cuboidal with cilia
  • Several layers of smooth muscle cells comprise a high proportion of the wall
• Clara cells / Exocrine bronchiolar cells


  • Nonciliated, dome-shaped apical ends with secretory granules
  • Functions: Secretion of surfactant, Detoxification, Antimicrobial peptides, Stem cells
• Smaller bronchi


  • Epithelium is primarily columnar cells with cilia, with fewer goblet cells
  • Lamina propria has both smooth muscle and small serous glands near cartilage
• Bronchioles


  • Intralobular airways with diameters of 1mm or less
  • Lack both mucosal glands and cartilage
• Large bronchioles


  Ciliated pseudostratified columnar epithelium
• Terminal bronchioles


  • Ciliated simple columnar or simple cuboidal epithelium
  • Last part of air conducting system
  • Becomes flattened as it approaches lung alveoli which is lined by simple squamous epithelium