Lung Microanatomy Flashcards
Beginning with the trachea, describe the conduction system.
Trachea–>Left and right primary bronchi–>Secondary/lobar bronchi (5 total, 3 right 2 left) –>segmental bronchi (10 in right, 8 in left)–>smaller bronchi–>bronchioles–>terminal bronchioles–>respiratory bronchioles–>alveolar ducts–>alveolar saccules
What’s the medical significance of the segments in the conduction system?
Each has its own blood and air supply, so if something goes wrong the segment can be resected without messing up other parts of the lung.
How can a blood vessel be differentiated from a bronchus or bronchiole?
Blood vessels have smooth muscle and thin endothelium. Bronchi have cartilage surrounding them. They usually run right next to each other.
Identify the layers of the wall of the trachea
Pseudostratified epithelial layer, lamina propria, submucosa of connective tissue, cartilage, adventitia.
Identify the layers of the wall of the bronchi
Pretty much the same as the trachea.
*Larger bronchi have smooth muscle between the epithelium and the submucosa.
Identify components of the endothelium of the trachea and the bronchi as well as their function.
Ciliated epithelial cells-move mucus/bacteria
Goblet cells-Secrete mucin to trap bacteria/immunity
Basal Cells
Neuroendocrine cells-release regulatory peptides
Identify key layers of the wall of the bronchiole
Submucosal layer beneath the lamina propria.
Ciliated cells and goblet cells in epithelia.
*NO CARTILAGE!!
What cells are found in greater abundance in the terminal bronchiole?
More club cells-these release surfactant and keep the alveoli from collapsing.
Briefly describe the pathologies of the following:
Cystic Fibrosis
Kartagener’s Syndrome
Smoking/Pollution (pertaining to epithelium)
CF=Chloride channel defect. Viscous mucus that can’t be moved effectively, chronic infections.
Kartagener’s=immotile cilia due to defects in dyneine arms. Chronic infections.
Smoking=loss of ciliated cells, change to squamous epithelium.
What are the 2 important cells found in the alveoli and where in the alveoli are they located?
Type 1 and Type 2 Pneumocytes
Found on side of alveolar septa that faces air supply.
T or F?
Type 2 alveolar cells are terminally differentiated and do not divide
False.
That’s Type 1. Type 2 cells are the progenitors for Type 1 cells, meaning they change into Type 1 cells to replenish them when they run low. Type 2 cells also secrete surfactant.
Which cell type shares a common basal layer with the endothelium in the alveolus?
Type 1.
Type 2 secretes out surfactant all over Type 1 cells since the Type 1 cells are embedded in the epithelium that faces the air supply, keeps it from collapsing.
What are the 3 major defense mechanisms in the alveoli or conduction system?
1) Alveolar macrophages move in and engulf particles/bacteria
2) Cilia sweep along bacteria/macrophages in the mucus flow out towards the respiratory bronchioles
3) Macrophages move into lymphatic system to serve as antigen presenting cells
*now you know what boogers consist of. yummy.
Describe the basic process of gas exchange at the blood-gas barrier. What role does surfactant play?
Dissolved gases go through surfactant layer, Type 1 pneumocyte, shared basal lamina of type 1 and endothelium, endothelium, and then RBC.
Surfactant decreases the surface tension, keeps lung from collapsing or becoming too dry.
What happens in black lung/silicosis/asbestos exposure?
Alveolar macrophages ingest something that they can’t break down and then die. Other macrophages ingest those dead macrophages and also die. This ends up staying deposited in the lung and leads to alveolar damage and less surface area for gas exchange.
