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26 Cards in this Set
- Front
- Back
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Describe the external nose
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leads to a vestibule, a dilated portion of the nasal cavity lined by stratified squamous epithelium which is inward continuation of the facial skin
epithelium has sweat and sebaceous glands; covered with special short thick hair called Vibrissae (entraps large particulate matter) |
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Describe the nasal cavity
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paired chambers divided by nasal septum; communicate with Nasopharynx posteriorly through choancae
Projecting from lateral wall of nasal cavity are 3 Conchae or turbinates (superior, middle and inferior); increase surface area and create turbulent airflow to allow more conditioning of inspired air nasal cavity is lined by respiratory and olfactory zones |
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Describe the sinuses
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communicate with the nasal cavity and inferiorly into the pharynx through posterior nares
lined by respiratory epithelium (PSCC) with numerous goblet cells |
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What are the functions of the sinuses?
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Passageway for air
cleans, Humidifies, and warms air Smell (olfaction) resonating chambers for speech |
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Describe the pharynx
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Common opening for digestive and respiratory systems
Nasopharynx-opens to nasal cavity through posterior nares; lined by pseudo-stratified columnar ciliated epithelium. Oropharynx-extends from soft palate to hyoid bone, laterally b/t palatine arches; opens through isthmus faucium into the mouth; mucosa lined by stratified squamous epithelium (SSE) Laryngopharynx-connects to esophagus; extends from epiglottis down to cricoid cartilage of the larynx; lined by non-keratinized SSE that covers lingual and apical laryngal surfaces of epiglottis |
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Describe the respiratory zone
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lines nasal septum and all surfaces of nasal cavity and conchae (except roof of nasal cavity, upper portion of nasal septum, and superior concha)
zone is formed by respiratory epithelium which is pseudostratified columnar ciliated epithelium (PSCC) with goblet cells |
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Describe the cells contained within the respiratory zone
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1. Ciliated columnar cells-constitute majority of the respiratory epithelium; has cilia projecting from apical surface that beats toward nasal cavity to clear air from particulates
2. Goblet cells-glandular simple columnar cells; apical portion usually distended with mucinogen granules that push nucleus and organelles toward the basal portion of the cell 3. Basal cells-Small, nearly cuboidal resting on the basal lamina; capable of differentiating 4. Granulated cells-unicellular; characterized by small granules in the cytoplasm (serotonin, calcitonin, enkephalins, and other neuropeptides); recognition of hypoxia (such as with high altitude) causes their release-->bronchodilation; also induce differentiation of lung epithelia 5. Endocrine cells-aggregate into Neuroepithelial Bodies 6. Brush cells: Non-Ciliated cells in the conducting portion; well-defined short microvilli and make epitheliodendritic synapse 7. Lymphocytes-found in mucosa of bronchi, where they form germinal centers and lymph nodules called BALT (Bronchi Associated Lymph Nodule) |
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Describe the function of swell bodies
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lamina propria of respiratory epithelium is highly vascular and contains smooth muscle, fibroblast, mast cells and elastic fibers
rich venous networks (swell bodies) in the lamina propria of respiratory epithelium are capable of becoming engorged with blood; One side swells every 20-30 min, directing air through other nasal fossa and allowing the delicate respiratory epithelium to recover from dehydration the vascular system of the nasal cavity results efficient warming of inspired air lamina propria continues with submucosal which contain seromucous glands (serous demilune) that help moisten inspired air |
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Describe the olfactory zone
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This zone is found lining roof of nasal cavity, upper portions of nasal septum and the superior concha
epithelium consists of pseudostratified columnar epithelium w/ modified bipolar cells (olfactory cells) in the middle level of the epithelium apical surface of the olfactory cell possesses long dendrite that extends beyond the surface epithelium forming olfactory knob; long cilia project from the knob olfactory epithelium lacks goblet cells; ends abruptly at a boundary with respiratory epithelium |
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Describe the contents of the olfactory zone
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1. Bowman’s glands-branched tubuloalveolar glands secrete fluid via a duct that opens onto olfactory surface; secretory fluid contains the odorant-binding protein (OBP) w/ high affinity for odorant molecules
2. Olfactory cilia-immotile, contain receptors for odiferous substances; Excitation of receptors stimulates cAMP production-->generates a receptor potential 3. Olfactory nerves-long axonal processes which enter the underlying CT to join axons of other bipolar olfactory neurons (mostly unmyelinated) 4. columnar sustentacular cells with microvilli-present in the upper level of epithelium 5. Basal and Brush cells which-close to basal lamina |
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Describe the conducting zone
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trachea to terminal bronchioles which is ciliated for removal of debris; mucus lined passageway
air movement is controlled by smooth muscle at end of terminal bronchioles Cartilage holds tube system open and smooth muscle controls tube diameter providing a passage for inhaled and exhaled air |
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Describe the functions of the larynx
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organ of phonation
closes trachea during swallowing to prevent food and saliva from entering the airway |
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Describe the larynx
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mucosa of larynx is continuous with pharynx and the trachea
lingual (upper) surface is covered w/ stratified squamous epithelium; Toward the base of the epiglottis, laryngeal (lower) side is respiratory epithelium Laryngeal seromucous glands are found throughout lamina propria (except at the true vocal cords) Below epiglottis, mucosa forms 2 folds; upper pair is false vocal cords, while lower pair is the true vocal cords false vocal cords are covered by respiratory epithelium with numerous serous glands in the lamina propria; true cords are covered by stratified squamous epithelium Beneath epithelium is vocal ligament and bundles of skeletal muscle (vocalis muscle) |
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Describe the trachea
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part of conducting system which extends from larynx to middle of thorax, lined by respiratory epithelium
has 16-20 C-shaped rings of hyaline cartilage in lamina propria which open posteriorly (serve to keep trachea open) fibroelastic tissue and a bundle of smooth muscle (trachealis muscle) bind to perichondrium and bridge gap b/t ends of the C-shaped cartilage; allows for contraction of lumen (used in cough reflex) trachea branches to form right and left primary bronchi entering hilum of each lung |
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Describe the bronchus
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Main or primary bronchi are formed where trachea bifurcates; structure is similar to trachea
After entering lung parenchyma, bronchi divide into secondary bronchi; right lung receives 3 lobar bronchi, left lung 2 lobar bronchi continues to divide and subdivide into tertiary and segmental bronchi, each supplying a bronchopulmonary segment; further subdivisions generate small subsegmental bronchi In branching bronchi, cartilage rings are replaced by cartilage plates, lamina propria contains a layer of discontinuous smooth muscle and serous glands lining surface of bronchi is similar to that of the respiratory epithelium Inhaled particles, liquids, microorganisms, and sloughed off epithelial cells w/in viscous layer are removed via ciliary action toward pharynx |
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Describe the small bronchi
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lining epithelium is pseudostratified columnar ciliated with mucus-secreting goblet cells
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Describe bronchioles
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Lacks cartilage and glands
pseudostratified ciliated columnar epithelium decreases in height to become simple columnar to cuboidal ciliated at the terminal bronchioles lamina propria is composed of smooth muscle and elastic and collagenous fibers |
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Describe terminal bronchioles
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last segment of conducting zone
terminal bronchiole and associated region of pulmonary tissues that it supplies constitute a pulmonary lobule the transition involves loss of cartilage plates in bronchiole and increase in number of elastic fibers and amount of smooth muscle which is wrapped around the bronchiole in criss-crossing bundles; diameter of airways can change due to contraction of the smooth muscle bundles pulmonary lobule includes respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli Terminal bronchioles are lined by ciliated cuboidal epithelium and Clara cells Clara cells-devoid of cilia, have dome like apical surface and cytoplasmic secretory granules against oxidative pollutants and inflammation; secrete a component of surfactant |
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Describe the respiratory portion of bronchioles
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Respiratory bronchioles to alveoli; Site for gas exchange
Respiratory bronchioles represent transition from conducting to the respiratory portion of the lung respiratory portion is composed of respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli (alveolus) |
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Describe respiratory bronchioles
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serve as transition zone b/t conducting and respiratory portions of respiratory system
mucosa identical to terminal bronchioles w/ simple, ciliated cuboidal epithelium distinguishing feature is the presence of scattered alveoli budding from walls of tubule Goblet cells are no longer present; Bundles of smooth muscle cells and elastic fibers are in wall and no glands in lamina propria |
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Describe the alveolar duct
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characterized by interrupted wall w/ smooth muscle knobs bulging into lumen and interposed b/t alveoli
distal end remnants of muscle knob are lined by low cuboidal to simple squamous epithelium; can be seen at alveolar openings distally the lining epithelium is primarily type I alveolar epithelial cells Alveolar ducts branch to form 2 or more alveolar sacs |
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Describe the alveolar sac
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terminal part of airway, formed by alveoli; wall of alveolar sac consists of alveolar openings
openings of alveolar sacs and alveoli are surrounded by elastic and reticular fibers; elastic fibers allow alveoli to expand upon inspiration and passively contract upon expiration; reticular fibers prevent over distension of alveoli, which would cause damage to the delicate capillaries and alveolar septa |
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Describe the alveoli
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terminal portion of the bronchial tree; responsible for spongy structure of the lungs
functional unit of the pulmonary lobule; provide large total surface area for O2 and CO2 exchange Each alveolus has an interalveolar septum |
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Describe the interalveolar septum
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form part of air-blood barrier; consists of 2 thin squamous epithelial layers b/t which lie capillaries, elastic and collagen fibers, macrophages and fibroblasts
septum b/t capillary lumen and alveolus is extremely thin and allows for ready exchange of 02 and C02 In order to allow for free flow of air between alveoli, septa are perforated by alveolar pores (Pores of Kuhn’s) alveolar epithelium consists of two cell types; Type I (40% of epithelial cells population but line 90% of alveolar surface); Type II alveolar cells (60% of cells covering 10% of surface) |
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Describe type II alveolar cells
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predominantly located at angles formed by adjacent alveolar septa; polygonal-shaped; free surface covered by short microvilli
synthesize and store pulmonary surfactants (phospholipids, protein and glycosaminoglycan-rich) in membrane bound lamellar bodies until release Surfactant is released by exocytosis and spreads over thin layer of fluid that normally coats alveolar surface; lowers surface tension at air-fluid interface and reduces the tendency of alveolus to collapse at the end of expiration additionally maintains and repairs alveolar epithelium when injury occurs |
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Describe other cells found w/in the alveolar septum
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other cells include fibroblasts, mast cells and brush cells
endothelial cells of capillaries are extremely thin; capillaries comprise “filling” of the septal sandwich; capillaries are continuous capillaries w/out fenestrations Alveolar macrophages (dust cells) found w/in septum and on surface of alveolar wall; can be passed up bronchial tree by the cilia and swallowed; other macrophages remain in CT of septum and scavenge along capillary wall alveolar membrane across which O2 and CO2 diffuse is less than half the thickness of interalveolar septum; consists of thin cytoplasm of type I cell, fused basal laminae of type I and capillary endothelial cells, and thin cytoplasm of capillary endothelial cell |
