Lecture 21: Pulmonary histology Flashcards
Respiratory mucosa consists of
Pseudostratified ciliated columnar epithelium
Lamina propria- thin layer of loose CT
Submucosa- dense irregular CT
Nares contain
Stratified squamous epithelium continuous with epidermis
Sebaceous, sudoriferous glands and hair follicles
Olfactory epithelium is
Pseudostratified columnar epithelium without goblet cells
No basement membrane
Sustenacular cells w/pigment granules
Basal cells w/pigment granules
Olfactory cells
Bipolar neurons
Apical end projects into nasal cavity and contains nonmotile cilia w/g-protein linked odor receptors
Basal end extends as unmyelinated axon to mitral cells in the olfactory bulb
Olfactory cells senesce and are replaced from basal cells
Olfactory glands of Bowman
Located in the lamina propria
Secrete odorant-binding protein
Odorant-binding protein binds to odorant molecules in nasal cavity
Nasopharynx mucosa consists of what epithelium
Respiratory epithelium
Waldeyers ring
Ring of lymphoid tissue around nasopharynx
Includes tonsils and adenoids
Epiglottis lingual surface
Covered with stratified squamous epithelium
Lamina propria with loose CT and elastic fibers
Epiglottis pharyngeal surface
Covered with pseudostratified ciliated epithelium
Lamina propria with tubuloacinar seromucous glands
Core of epiglottis consists of
Elastic cartilage
False vocal cords
Covered with pseudostratified ciliated and stratified squamous epithelium
Lamina with seromucous glands
True vocal cords
Covered with stratified squamous epithelium
Lack seromucous glands in lamina propria
Epithelium of larynx
Respiratory epithelium (pseudostratified ciliated columnar) Stratified squamous
Cartilage of larynx
Hyaline cartilage- thyroid, cricoid, arytenoids
Elastic cartilage- corniculates, cuneiforms, tips of arytenoids, epiglottis
Muscle in larynx
Skeletal muscle
Mucosa of trachea
Respiratory epithelium w/thick basement membrane
Lamina propria w/delicate FECT and lymphatic tissue
Submucosa of trachea
Contains many seromucous glands
Adventitia of trachea
16-20 horseshoe-shaped cartilages interconnected by FECT
Mixed glands and capillaries
Trachea divides into two
Bronchi
Each primary bronchus divides into
Three (to right lung) or two (to left lung) secondary bronchi, also referred to as lobar bronchi
As the bronchi become smaller, there is a
Decrease in the height of the epithelium, decrease in cartilage and glands, and an increase in the proportion of elastic fibers and smooth muscles
Mucosa of bronchi
Similar to trachea
May have mucosal folds due to smooth muscle
Elastic fibers are prominent
Submucosa of bronchi
Characterized by loose CT and lymphatic tissue
Contains mixed glands and mucous glands
Adventitia of bronchi
Contains hyaline cartilage plates surrounded by dense FECT
Characteristics of bronchioles
Absence of cartilage and glands
Sparse goblet cells
Large amounts of smooth muscle tissue
Epithelium transitions from ciliated columnar with few goblet cells to ciliated cuboidal with no goblet cells (terminal bronchioles)
Characteristics of respiratory bronchioles
Epithelium of low columnar to low cuboidal
Cilia present only in larger respiratory bronchioles
No goblet cells
Wall consists of smooth muscle within FECT
May have a few alveolar outpocketings
Alveolar ducts
Continuations of respiratory bronchioles
Cone shaped
Squamous epithelium
Wall consists of smooth muscle within FECT
Type I alveolar cells (pneumocytes)
Less numerous than type II pneumocytes
Cover largest surface area (95% of alveolar surface)
Very thin cytoplasm
Tight junctions connect with other Type I cells
Type II alveolar cells (pneumocytes)
Cuboidal or rounded
Serve as stem cells for type I and type II pneumocytes
Produce phospholipid-protein surfactant that coats alveolar walls
Pores of Kohn
Openings between adjacent alveoli
Goblet cells
Mucous secreting cells
Also stem cells; can replace other cells of epithelium
Neuroendocrine cells
May be associated with sensory reception and are more prevalent in infants
Release catecholamines
Surfactant
Secreted by Clara cells and type II alveolar cells
Reduces surface tension on alveolar cells
Phagocytized by type II alveolar cells
Dipalmitoyl phsophatidycholine (lecithin)
Found in lamellar bodies in Type II alveolar cells
Secreted from apical domain
Combines with proteins from Clara cells
Clara cells
Only found in broncholes
Number of Clara cells increases as ciliated columnar cells decrease
Apical surface bulges into lumen of airway
Secrete lipoprotein that prevents collapse of terminal bronchioles during exhalation
Contain abundant SER
Dust cells
Macrophages in respiratory tract
Dust cell relation to CHF
In CHF, fluid containing the breakdown products of hemoglobin leak into alveolar spaces and are phagocytized by dust cells
The iron containing dust cells are referred to as heart failure cells
Components/function of blood air barrier
Thin capillary endothelium (continuous)
Thin epithelium of pneumocyte
Intervening basil lamina produced by both cell types
Permits gas exchange but does not allow fluids or cells to enter alveoli
