Lecture 29: Pulmonary Histology Flashcards
What epithelium lines the nares?
Stratified squamous epithelium continuous with epidermis; nares contain sebaceous and suderiferous glands and hair follicles
What is respiratory epithelium?
Pesudostratified ciliated columnar epithelium
Olfactory epithelium
located in nasal cavity roof; respiratory epithelium WITHOUT goblet cells; no distinct basement membrane
Sustentacular cells
Support cells with pigment granules (olfactory epithelium)
Basal cells
Have pigment granules; stem cells - give rise to immature olfactory cells (olfactory epithelium)
Olfactory cells
Bipolar neurons; apical end projects into nasal cavity as knoblike ending w/ non-motile cilia (G-protein linked odor receptors); basal end of cell extends as unmyelinated axon bundled with other similar axons through the ethmoid plate to mitral cells located in olfactory bulb; senesce and replaced by basal cells
Olfactory glands of Bowman
Located in lamina propria, secrete odorant binding protein which binds to odorant molecule in nasal cavity
Waldeyer’s Ring
Ring of lymphoid tissue around nasopharynx which includes tonsils and adenoids; “portal” in back of nasopharynx that encounters airborne antigens and initiates immune response
Lingual surface of epiglottis
Covered with stratified squamous epithelium; lamina propria with loose CT and elastic fibers
Pharyngeal surface of epiglottis
Covered with respiratory epithelium; lamina propria with tubuloacinar seromucous glands
False vocal cords
Covered with respiratory epithelium, lamina with seromucous glands
True vocal cords
Covered with stratified squamous epithelium, lack seromucous glands in lamina propria
Name all 5 tissues found in larynx
Respiratory epithelium, stratified squamous epithelium, hyaline cartilage, elastic cartilage, skeletal muscle
Mucosa of trachea
Respiratory epithelium, thick basement membrane; Lamina propria with delicate FECT and lymphatic tissue
Submucosa of trachea
Many seromucous glands
Adventitia of trachea
16-20 horseshoe shaped cartilages interconnected by FECT which are closed by trachealis muscles, mixed glands and capillaries
Bronchi
2 primary - one to each lung; extrapulmonary; resemble trachea except for smaller diameter and circular cartilage rings
Secondary bronchi
Each primary divides into 3 on the right, 2 on the left; AKA segmental bronchi - mostly intrapulmonary; circular rings of cartilage transition into irregular plates
What happens to histological characteristics of bronchi as they decrease in size?
Height of epithelium decreases, there is a decrease in cartilage and glands, and an increase in proportion of elastic fibers and smooth muscles
Mucosa of intrapulmonary bronchi
Similar to trachea and extrapulmonary bronchi; mucosal folds present due to smooth muscles, elastic fibers prominent
Submucosa of intrapulmonary bronchi
Characterized by loose CT and lymphatic tissue, contains mixed glands and mucous glands
Adventitia
Contains hyaline cartilage plates surrounded by dense FECT
Name some characteristics of bronchioles
Absence of cartilage, glands; sparse goblet cells, mostly smooth muscle; ciliated columnar to ciliated cuboidal; terminal bronchioles form 2 or more respiratory bronchioles
Name some characteristics of respiratory bronchioles
Low columnar/cuboidal epithelium, cilia present only in larger respiratory bronchioles; no goblet cells, smooth muscle wall within FECT; some alveolar outpocketings as gas exchange occurs here first
Alveolar ducts
continuation of respiratory bronchioles, cone-shaped and made of squamous epithelium with smooth muscle/FECT
Alveoli
Several within each alveolar sac; separated by thin alveolar septa; walls composed of Type I, II alveolar cells, macrophages, contain Pores of Kohn
Type I alveolar cells/pneumocytes
Less numerous than Type II, but cover largest surface area (more spread out); very thin cytoplasm, tight junctions connect with other type I cells, basal lamina may be fused with basal lamina of nearby capillaries
Type II alveolar cells/pneumocytes
Cuboidal/rounded-bulge into alveolar lumen, serve as stem cells for type I and type II pneumocytes; contain numerous lamellar bodies with lecithin which is a component of surfactant; these cells can also phagocytize old surfactant
Pores of Kohn
Openings between adjacent alveoli - collateral respiration
Neuroendocrine cells
May be associated with sensory reception and more prevalent in infants; release catecholamines
Clara cells
Found only in bronchioles; secrete protein which is a component of surfactant; number increases as ciliated columnar cells decrease; apical surface bulges into lumen of airway; abundant SER for lipid synthesis
Dust cells/macrophages
derived from monocytes, phagocytize particles not trapped in mucous; connection to CHF: fluid containing hemoglobin breakdown products leak into alveolar spaces and phagocytized by dust cells - iron-containing dust cells are referred to as heart failure cells
Blood-Air Barrier
Consists of: thin capillary endothelium, thin epithelium of pneumocyte, intervening basal lamina produced by both cell types; permits gas exchange but does NOT allow fluids or cells to enter alveoli
