Respiratory System Histology - Downing Flashcards
What is respiratory epithelium (3 types of cells)?
Respiratory epithelium of mucosa =
- Goblet cells (30%): mucus secretion
- Ciliated columnar cells (30%): move mucus
- Basal cells: (30%) mitotic, undifferentiated; replenish goblet, ciliated columnar, and brush cells
Where is olfactory epithelium found? What is it composed of?
Where = limited region of posterior nasopharynx What is it = -Bipolar cells (neuronal cells) -Sustentacular cells (supporting cells) -Basal cells (mitotic cells) -Lamina propria
What are the differences between the functions of the conducting and respiratory division of the respiratory system?
Conducting - warms, moistens, & filters air. Delivers air to respiratory division. No gas exchange.
Respiratory - function = gas exchange
What are the histological features of the anterior nasopharynx?
Anterior portion = vestibule
- Lined with skin
- Coarse hairs: vibrissae (stop from inhaling foreign bodies)
- Dermis contains sebaceous and sweat glands
What are the histological features of the oropharynx?
Stratified squamous epithelium
What are the histological features of the laryngeal pharynx?
Stratified squamous epithelium
What are the histological features of the larynx?
Short cylindrical tube (4 cm x 4 cm)
Cartilages reinforce laryngeal wall:
- Hyaline cartilages = *thyroid, *cricoid
- Elastic cartilages = *epiglottis
- Cartilages connected by ligaments = movements controlled by intrinsic and extrinsic skeletal muscles
What are the 3 histological layers of the trachea?
- Mucosa
- Submucosa
- Adventitia
What are the histological features of the Intrapulmonary bronchi?
- C-shaped cartilage rings replaced by irregular *plates of hyaline cartilage
- Smooth muscle at interface of lamina propria and submucosa in two distinct layers
- Seromucous glands and lymphoid elements present in submucosa
- Pseudostratified ciliated epithelium on mucosal surface
- **Presence of alveoli
What are the histological features of the Non-olfactory region of the posterior nasopharynx?
Non-olfactory regions:
- Respiratory epithelium = pseudostratifed ciliated columnar epithelium
- -Richly vascularized
- -Seromucous glands (in underlying connective tissue)
- -Many lymphoid elements = lymphoid nodules; mast cells; plasma cells (produce IgA, IgE, and IgG)
- –Protects nasal mucosa from inhaled antigens and microbial invasion
What are the histological features of the Olfactory region of the posterior nasopharynx?
Small region of roof of nasal cavity; superior aspect of nasal septum; superior concha
Olfactory epithelium:
- Bipolar cells
- Sustentacular cells
- Basal cells
- Lamina propria
What are the histological features of the Epiglottis?
- Supported by a core of *elastic cartilage
- Superior surface = stratified squamous epithelium
- Inferior surface = pseudostratified ciliated columnar epithelium
What are the histological features of the Vestibular (ventricular) fold of the Larynx?
- Superior location
- Immovable
- Pseudostratified ciliated columnar epithelium
- Lamina propria
What are the histological features of the Vocal fold of the Larynx?
- Inferior position
- Reinforced by the elastic vocal ligament
- Vocalis muscle attaches to vocal ligament
- Superior surface covered with stratified squamous epithelium
What are the histological features of the Mucosa layer of the Trachea?
Pseudostratified ciliated columnar epithelium
Thick basement membrane
Lamina propria
-Loose fibroelastic tissue
-Lymphoid elements
-Mucous and seromucous glands
-Elastic lamina separates lamina propria from underlying submucosa (rings of fibers)
What are the histological features of the Submucosa layer of the Trachea?
Dense irregular fibroelastic connective tissue
Mucous and seromucous glands
Lymphoid elements
Rich vascular and lymph supply
What are the histological features of the Adventitious layer of the Trachea?
Fibroelastic connective tissue
C-shaped hyaline cartilages
Anchors trachea to esophagus
What type of cartilage forms the C-shaped rings on the trachea?
Hyaline cartilage
-Open ends face posteriorly; joined by smooth muscle (trachealis muscle)
Where is respiratory epithelium found?
Trachea
What are histological trends as you descend down the bronchial tree?
As you go down bronchial tree:
- Decreasing amounts of cartilage, glands, goblet cells, and epithelial height
- Increasing amounts of smooth muscle and elastic tissue
How do you differentiate a bronchus from a bronchiole?
Bronchus: cartilage present (plates of cartilage)
Bronchiole: no cartilage
What are the histological features of the bronchioles?
Epithelium:
- Larger bronchioles = ciliated simple columnar with goblet cells
- Smaller bronchioles = Simple cuboidal (some ciliated) with club (“Clara”) cells and no goblet cells
Lamina propria: smooth muscle; no glands and ***NO cartilage; abundant elastic fibers in connective tissue surrounding the smooth muscle
What are the function(s) of club (“Clara”) cells?
- Secretory granules in apical cytoplasm
- Secretory product protects bronchiolar epithelium
- Help degrade toxins via cytochrome P-450 enzymes in smoother (detoxifying)
- Produce a surfactant-like material
- Divide and help replenish epithelium
Where are club (“Clara”) cells found?
smaller bronchioles
- look like clubs
- replace Goblet cells
