Historlogy Of The Resoritory System Flashcards
Functions of the respritory system
Gas exchange (primary function), olfaction, and phonation (production of sound)
Conditioning
As air travels to site of gas exchange it is warmed humidified and cleared of particulate matter in this process which is known as conditioning
Conduction portion of respritory system
Begins at the nares and consists of all air passages that lead to site of gas exchange in lungs, air is conditioned as it passes through conduction portion of respritory system
Nasal Cavity respritory system
Air enters through nares and into nasal vestibule (lined by stratified squamous epithelium, contains hairs to entrap large particulate matter). Respritory portion nasal cavity lined by respritory mucosa which consists of ciliated pseudostratified columnar epithelium has thin underlying lamina propria. Epithelium consists of two cell types ciliated and goblet
Ciliated cells of respritory system
Tall and columnar with cilia that project and into mucus covering epithelial surface
Goblet cells of respritory system
Synthesize and secrete mucus have a distended apical cytoplams packed with mucinogen granules, stem portion is occupied by condensed basal nucleus and other organelles involved in synthesis of mucinogen (mucinogen washed out in H&E staining)
Lamina propria respritory system
Underlying respritory epithelium, has rich vascular network which warms inspired air, also contains serous and mucous glands which secrete fluid and mucus onto epithelial surface
Conchae
Cartilagenous scrolls that are covered in mucosa these project from dorsal and lateral walls of nasal cavity and increase its surface area. These increase efficiency of warming inspired air and turbine precipitation of particulate matter (air enters conchae breaks into eddies trapping particles of air in mucous covering epithelium, these particles are transported to the pharynx via coordinated sweeping movements of cillia where they can be swallowed or expectorated
Pharynx
Air passes from nasal cavity into nasopharynx and laryngopharynx which are lined by respritory epithelium. Lamina propria form tonsils from gland and lymphoid tissue
Larynx
Forms passage of air between oropharynx and trachea, mostly lined with ciliated pseudostratified columnar epithelium. Vocal folds and epiglottis are covered by stratified squamous epithelium
Trachea
Consists of 4 tunics tunica mucosa, tunica submucosa, tunica muscularis, tunica adventitia
Trachea tunica mucosa
Ciliated pseudostratified columnar epithelium, supported by elastic fiber rich lamina propria. NO clear boundary between lamia propria and submucosa
Trachea tunica submucosa
Denser connective tissue than lamina propria
Submucosa contains serous (or seromucous glands depending on the species) and blood vessels which aid in warming and humidifying air. Very cellular, many lymphocytes, plasma cells, eosinophils, mast cells, and fibroblasts. Lymphatic tissue in diffuse and nodular forms
Tunica muscularis trachea
Contains c shaped cartiledges open dorsally which keep lumen of trachea open. Open ends of cartilage rings are bridged by smooth muscle and elastic fibers
Tunica adventitia
Connective tissue binding trachea to adjacent structures
Tracheal epithelium
Contains ciliated and goblet cells that make up mucocilliary escalator where particles are entrapped by mucus and swept toward pharynx by coordinated movement of cillia. There is a population of basal cells which are pro generators of other cell types
Bronchi
Trachea bifurcates into left and right primary bronchi, when entering the hilum of the lung each main bronchi divides into lobar bronchi, each of which enter a lung lobe, within each lobe these further divide to become segmental bronchi
Bronchi histology
Very similar to that of trachea can be identified bc of cartilage plates and circular layer of smooth muscle as bronchi decrease in diameter with each division cartilage plates become smaller and less numerous and cells of epithelium become shorter
Bronchioles
Air conducting ducts <1mm diameter, formed by branching of segmental bronchi, ducts branch and give rise to terminal bronchioles and ultimately respritory bronchioles. No cartilage or glands, thick layer of smooth muscle
Transition from ciliated pseudostratified columnar epithelium with goblet cells in large diameter bronchioles, to simple ciliated columnar epithelium, finally simple ciliated cubodial epithelium in smallest conducting bronchioles
Cell clubs
Aka bronchiole exocrine cells Present in epithelium of terminal bronchioles non-ciliated cells with rounded or dome shaped apical surface projection secrete surface-active agent which keeps airway from adhering to itself should it collapse, also make other components of airway secretions and detoxify substance inhaled into lungs. # ciliated cells decreased # club cells increase
Respritory bronchioles
Terminal bronchioles branch into respritory bronchiles which are first part of bronchial tree to allow gas exchange (these are involved in air conduction and gas exchange). Narrow in diameter and lined with cuboidal epithelium composed of ciliated and club cells. Scattered alveoli extend from lumen of respritory bronchioles
Alveolar system
Alveoli are site of gas exchange, they are thin walled polyhedral chamber surrounded by capillary networks
Alveolar ducts
Respritory bronchioles branch into alveolar ducts which consist of alveoli arranged to form tube. These terminate in alveolar sac
Alveolar septum
Aka alveolar wall, tissue between adjacent alveolar air spaces
