flashcards

• Respiratory system


  Consists of two major components - the conductive and the respiratory parts
• Conductive portion


  Transports, cleanses and humidifies as well as cools or warms the inspired air. Specific portions are responsible for olfaction and phonation
• Respiratory part


  Site of the actual exchange of gases
• Conductive portion


  • Includes all the structures from the nares to the terminal bronchioles
• Respiratory portion


  • Starts from the respiratory bronchiole in the alveoli
• Nasal cavity


  • Has 3 regions: vestibular, respiratory and olfactory regions
• Vestibular region


  Represents the point of reflection of the skin as the mucous membrane of the nasal cavity
• Respiratory region


  • Comprises the bulk of the nasal cavity, lining epithelium is pseudostratified ciliated with goblet cells, muscularis mucosae is absent, lamina propria-t.submucosa is areolar connective tissue, glandular tissue humidifies the air while the engorged erectile tissue cools or warms it
• Olfactory region


  • Specialized area for olfaction, lining epithelium is pseudostratified columnar nonciliated, very thick with up to 15 layers of nuclei
• Sustentacular cell


  Tall with broad apices and narrow bases, nucleus is oval, vesicular and located towards the apex
• Basal cell


  Cuboidal in shape
• Olfactory cells


  Modified neurons, basal processes continue to the brain as axons of the first cranial nerve, apex has a bulb-like projection with cilia/olfactory hairs as receptors, nucleus is round vesicular and located centrally or basally
• Bowman's glands


  Branched tubuloalveolar serous glands responsible for cleansing olfactory surface and dissolving odor producing substances
• Nasopharynx


  • Lining epithelium is pseudostratified columnar ciliated, no muscularis mucosae, lamina propria - t. submucosa consist of loose connective tissue with numerous diffuse and nodular lymphatic tissue and tonsils, t. muscularis is skeletal muscle in various orientation, t. adventitia is continous with underlying fascia
• Larynx


  • Lining epithelium is either stratified squamous or pseudostratified columnar ciliated, no muscularis mucosae, lamina propria-t. submucosa is areolar connective tissue with diffuse and nodular lymphatic tissue and branched tubuloalveolar mucous, serous and mixed glands, t. muscularis consist of striated muscle and cartilage, t. adventitia is typical
• Trachea


  • Lining epithelium is pseudostratified columnar ciliated with goblet cells, basal cells, brush cells, serous cells, Clara and Kultschitzky or neuroendocrine (APUD) cells, no muscularis mucosae, lamina propria-t. submucosa is areolar c.t. with branched coiled tubuloalveolar mucous glands, t. muscularis is reduced to a transversely oriented mass of smooth muscle (trachealis muscle), t. adventitia is typical and blends with surrounding fascia
• Extrapulmonary bronchi


  • Structurally similar to trachea
• Lung


  Structurally considered as a compound tubuloalveolar gland, its excretory product, carbon dioxide is "secreted" across the alveolar surface in exchange for the uptake of oxygen
• Types of Lung


  • Type I (Ruminants and pigs)
  • Type II (Dog, cat and monkey)
  • Type III (Horse and human)
• Type I Lung


  • With well-developed secondary lobules, thick interlobular septa and thick pleura, alveoli between lobules are without interalveolar pores of Kohn, complete interlobular septa extending from visceral pleura to c.t. surrounding major bronchi and blood vessels
• Type II Lung


  • Without secondary lobules, with poorly developed intraparenchymal supportive tissue strands, with thin visceral pleura
• Type III Lung


  • Incompletely developed secondary lobules, well-defined but disorderly arrangement of interlobular septa, thick visceral pleura
• Intrapulmonary bronchi


  • Same structure as extrapulmonary bronchi except muscularis is present, subdivided into primary, secondary and tertiary bronchi, lining epithelium is pseudostratified columnar ciliated with goblet cells, lamina propria is areolar, muscularis mucosae is present, t. submucosa is areolar with branched, coiled tubuloalveolar mucous glands
• Bronchioles


  • Lining epithelium is simple columnar or simple cuboidal cells and is devoid of goblet cells, lamina propria is fine collagenous and elastic fiber, muscularis mucosae is present and continuous, cartillage is absent
• Respiratory bronchioles


  Initial portion of lung responsible for the exchange of gases, transition zone
• Respiratory bronchioles


  • Lining epithelium is simple cuboidal, some which are ciliated, interrupted by alveoli that outpocket from the walls, lamina propria is indistinct, muscularis mucosae is present but loosely organized
• Terminal bronchiole


  Most distal conducting airway free of alveoli, lined by simple columnar or cuboidal epithelium composed of ciliated and Clara cells
• Clara cells


  Bronchiolar exocrine cells with secretory function and capable of metabolizing xenobiotic compounds
• Alveolar ducts


  • Completely lined by alveoli, smooth muscle may be present along the luminal border at the apices between adjacent alveoli, divide and expand peripherally into alveolar sacs or saccules which are completely lined by alveoli
• Alveoli


  Spheroidal air spaces, lined by two types of cells: Type I pneumocytes for gaseous exchange, Type II pneumocytes for producing alveolar fluid with pulmonary surfactant
• Interalveolar septa


  • Thin sheets of tissue separating adjacent alveoli, containing a capillary plexus and covered on both sides by a layer of epithelium (Type I & II pneumocytes) and capillary endothelial cells attached to a continuous basal lamina
• Arterial systems of the lung

  • Pulmonary artery and its peripheral subdivisions
  • Bronchial arteries
• Avian respiratory system


  • Upper respiratory tract includes structures described for mammals plus the syrinx, lungs are extremely small compared to thoracic cavity and do not change volume during inhalation and exhalation, air sacs are continuous with the duct system of the lung, primary bronchi are distinctly different from mammals
• Syrinx


  • Located at the junction of the trachea and bronchi, an inverted Y-shaped structure with a cartilaginous bar and a mucosal/submucosal fold to constitute the median vocal fold, two lateral vocal folds are produced upon drawing the bronchi toward each other, lining epithelium is bistratified squamous or simple columnar, lamina propria presents mucosal glands as well as diffuse and nodular lymphatic tissue
• Cartilage rings replaced by DWFCT and smooth muscle


  1. Cartilage rings replaced

  2. Smooth muscle connects free surfaces of cartilage
• Syrinx


  • Located at junction of trachea and bronchi
  • Inverted Y-shaped structure
  • Cartilaginous bar with mucosal/submucosal fold to constitute median vocal fold
  • Two lateral vocal folds produced upon drawing bronchi toward each other
• Syrinx lining epithelium


  • Bistratified squamous or simple columnar
• Syrinx lamina propria


  • Presents mucosal glands and diffuse/nodular lymphatic tissue
• • Lungs are extremely small compared to thoracic cavity
  • They are not expandable and do not change volume during inhalation/exhalation
  • The structures that change are the air sacs which are continuous with the duct system of the lung
• Avian bronchial tree


  • Primary bronchi enter lung and expand as vestibulum
  • Vestibulum continuous as mesobronchus and connected to abdominal air sac
  • Secondary bronchi and air sacs arise from vestibulum and mesobronchus
  • Secondary bronchi give rise to tertiary bronchi or parabronchi continuous with secondary bronchi forming complete air conducting loop
  • Parabronchi analogous to alveolar ducts of mammals