Lung histopathology Flashcards
What are the air conducting portions of the airways?
Air conducting portion:
- Nasal cavities
- Nasopharynx
- Larynx
- Trachea
- Bronchi
- Bronchioles
What is the respiratory portion of the respiratory tract?
Respiratory portion:
- Respiratory bronchioles
- Alveolar ducts
- Alveolar sacs
- Alveoli
How is the air conducting portion lined?
Air conducting portion:
Epithelial lining + surrounding support tissues (cartilage, smooth muscle, elastic fibres)
How is the respiratory portion lined?
Respiratory portion:
Simple squamous epithelia + scant (!) loose connective tissue → For optimal gas (O 2 /CO 2 ) diffusion
Look at this airway diagram?
What does respiratory epithelium look like?
Respiratory epithelium.
Brush cells have microvilli; are thought to be sensory receptors in association with the trigeminal nerve
The trachea terminates by bifurcating into?
Two primary (main) bronchi
Each primary bronchus divides one or more times into?
intrapulmonary bronchi ( secondary and tertiary bronchi )
Look at this histology of the bronchi?
Discuss bronchioles?
Branch from the intrapulmonary bronchi, ending as terminal bronchioles
- More distally, the respiratory epithelium becomes simple columnar or simple cuboidal (still ciliated!)
- Epithelium with Clara cells (= bronchiolar exocrine cells) -
- Without (!) cartilage and glands e:epithelium m:smooth muscle
Discuss respiratory bronchioles?
A continuation of a terminal bronchiole, interrupted by thin- walled outpocketings (= alveoli ) → Both air conduction and gas exchange ( transitional )
Epithelium:
Alveoli: simple squamous
Bronchioles: simple cuboidal
The amount of respiratory bronchioles vary among animal species ( carnivores >> herbivores; absent in humans and small rodents)
Look at this respiratory bronchiole?
The wall of the bronchiole is covered by ciliated epithelium, which is supported by smooth muscle and connective tissue. Terminally, the wall becomes interrupted, forming lateral communications between the bronchiolar lumen and alveoli (arrows)
What is the alveoli?
Site of gas exchange between the air and the blood (!)
Alveolar ducts: Elongated airways that are lined by alveoli only
Alveolar sacs: Spaces surrounded by clusters of alveoli
Alveolar septum (= septal wall): Tissue between adjacent alveolar air spaces
How do alveoli appear on histology?
What are type 1, 2 alveolar cells and brush cells?
Type 1 alveolar cell (type 1 pneumocyte):
Very thin squamous cell, line 95% of the alveolar surface
Type 2 alveolar cell (type 2 pneumocyte):
Cuboidal cell, secretes surfactant, cover ~ 5% of the alveolar surface
Brush cell (rare)
How does normal lung appear histologically?
How does lung pathology appear?
