Wk.11 L2 - Histology of the respiratory system Flashcards
(20 cards)
LO
- Identify and describe the histological features of the olfactory mucosa
- Identify the main regions of the respiratory tract based on histological features
- Identify the types of cells present in the respiratory epithelium
- Describe the cellular and structural elements that form the blood-air barrier
- Apply your knowledge to explain the process of breathing and filtering the air
Olfactory mucosa
Olfactory epithelium = pseudostratified columnar
Four types of cells:
1. Olfactory receptor (Bipolar neuron, nuclei inmiddle)
2. Sustentacular (columnar epithelia, nucleus apical)
3. Brush
4. Basal (nuclei at base)
Lamina propria:
- Loose CT, very cellular
- Olfactory nerves and serous-mucous glands
Olfactory Bipolar neuronal cells
- For smell
- Seen under silver stain
- Apical surface has cilia (non-motile) and single dendrite extends into lumen
- Axonal process leaves cell and entres lamina propria to form CN1 olfactory nerve
Olfactory mucosa - Sustentacular cells
Function:
- metabolic (secrete odorant-binding proteins) and physical support role
.
- Most common cell type in olfactory epithelium
- Columnar epithelia with microvilli
- Nucleus in an apical position
Olfactory mucosa - Brush cells
Columnar cells with microvilli
Nuclei at base
Basal plasma membrane synapses with axons from trigeminal nerve
Function = Sensation
Olfactory mucosa - Basal cells
Small round
Differentiate into sustentacular cells
Function = stem cells
Respiratory Epithelium
4 cell types:
* Goblet cells
* Brush cells
* Basal cells
* Ciliated pseudostratisfied columnar epithelium
Thick basement membrane to act as a protective layer and help regrowth oif columnar epithelium
Respiratory Epithelium - Goblet cells
Unicellular glands
Secrete mucous
Increase in number during inflammation
Nucleus at base
Respiratory Epithelium - Brush cells
Columnar epithelia
Microvilli
Hard to identify
Respiratory Epithelium - Basal cells
Cuboidal stem cells
Respiratory airways
4 Layers:
- Epithelium (mucosa)
- Lamina Propria (mucosa)
- Submucosa
- Adventitia
Respiratory airways - Mucosa
Epithelium:
- Ciliated Pseudostratisfied columnar
- Rests on thick basement membrane
Lamina Propria:
- Loose CT
- Many cells, some elastin fibre
Respiratory airways - Lamina propria
loose connective tissue, very vascular and very cellular
Respiratory airways - Submucosa
Loose CT (gradual change from lamina propria)
Anini of sero-mucous glands with smooth muscle
Hyalin Cartilage surrounded by dense perichondrium
Respiratory airways - Adventitia
- Variable amount of CT
- Continuous with oesophagus
- Binds trachea to oesophagus and other neck structures (vessels)
Pleura (Serosa)
- Simple squamous epithelium
- Loose CT
Visceral Pleura = Lung side
Parietal Pleura = Thoracic cavity/ costal side
Bronchus
Mucosa:
Epithelium = Ciliated pseudostratisfied columnar epithelium
Lamina Propria = Loose CT & many cells
Submucosa:
- Loose CT
- Continuous smooth muscle
- submucosal glands (mucous secreting)
- Hyalin cartilage (plates)
Adventitia:
- Variable amounts of dense irregular CT
Bronchioles
Mucosa:
Epithelium = Simple Columnar/ Cuboidal
Lamina Propria = Thin loose CT layer
Submucosa:
- Continuous smooth muscle layer
- NO submucosal glands or cartilage
Adventitia:
- not obvious
Terminal bronchiole -> Respiratory bronchiole
Alveolar ducts and alveolus
Type 1 Alveolar cells:
- Squamous (95%)
- Zonula Occuldens
- Cannot divide
Type 2 Alveolar cells:
- Secrete surfactant (5%)
- Cuboidal
- May divide into type 1 when theres injury
Macrophages:
- In alveolar septum & lumen of alveoli
Air-Blood barrier
- Part of alveolar septum where gas exchange occurs
Made of:
- Surfactant
- Type 1 cells
- Endothelial cells
- Fused basement membrane
- NO NUCLEUS (too large)
Air pathway:
Alveolar lumen
Alveolar septum (Cells listed)
Capilary lumen
