Respiratory tract Flashcards
Conducting vs respiratory airway
Conducting airway
• Nose→terminal bronchioles (in lungs)
• Filters, warms and moistens air
• more cartilage
Respiratory airway
• Respiratory bronchioles→alveoli
• Gas exchange between air and blood
• more elastic
Upper respiratory tract location, function and mucosa
Paranasal sinuses – lighten the skull weight and increase resonance in speech
Respiratory mucosa – Pseudostratified columnar ciliated epithelium
Lower respiratory tract components
Conducting respiratory system epithelium
Pseudostratified columnar ciliated epithelium which contains:
Ciliated cells
Goblet cells
Basal cells
K cells
Underlying lamina propria
Roof of nasal cavity epithelium
Olfactory
Sustentacular cells- are believed to provide physical support, nourishment, and electrical insulation for the olfactory cells.
Bowman/olfactory glands- dissolve odoriferous particles/their secretion may act as the solvent in which odorous substances dissolve.
Kulchitsky (k) cells
Neuroendocrine cells that contain secretory granules eg. Serotonin and found in psuedostratified columnar epithelium
Mucociliary clearance
Pathogens trapped in mucus
Cilia beat in unidirectional fashion to clear mucus towards the pharynx
Trachea schematic
Blood air barrier
Made up of:
Alveolar epithelium
Fused basement membrane of alveolar epithelium and capillary endothelium
Capillary endothelium
Trachea histology
Bronchus histology
Respiratory portion of bronchioles
Terminal bronchioles histology
Alveolar types
Type I Pneumocytes
Squamous epithelia covering 95% of alveolar surface
Form the extremely thin gaseous diffusion barrier.
Nuclei = flattened. Less likely to be seen in light microscopy
Type II Pneumocytes
60% of total alveolar cells but 5% of surface.
Produce surfactant –prevents collapse of alveoli.
Have rounded nuclei
Interstitial space
contains elastic fibres - paramount in breathing (elastic recoil), between 2 tissues or cells
Squamous metaplasia
Bronchial tree summary
Red – extrapulmonary (includes nasal cavity and pharynx)
Black – Intrapulmonary
1. Layers become thinner as passageways decrease in diameter.
2. Epithelium decreases in height from pseudostratified to simple columnar to simple cuboidal to simple squamous.
3. Goblet cells and mixed glands stop relatively abruptly at the junction of a secondary bronchus with a bronchiole.
4. Cartilage decreases in size, breaks up into plates, and stops relatively abruptly at the junction of a secondary bronchus with a bronchiole.
5. Cilia are gradually eliminated.
6. Trachea bifurcates at T4
