Histology: lungs

Question 1

What comprises the upper airways?
What comprises the lower airways?
- What comprises the conducting zone?
- What comprises the respiratory zone?

Answer 1

Larynx up
Trachea down
Trachea - terminal bronchioles
Respiratory bronchioles - alveolar sacs (where there are alveoli)

Question 2

Differences between cartilage in trachea and bronchi?
What structures run anteriorly with the trachea?

Answer 2

No longer C shaped
The thyroid and carotid artery

Question 3

What are the common features of the trachea and bronchi?

Answer 3

Epithelium
Hyaline cartilage
Smooth muscle
Submucosal/seromucus glands

Question 4

3 types of epithelial cells in trachea and bronchi?

Answer 4

Pseudostratified ciliated columnar epithelium
Goblet cells
Basal cells (stem cells, can have local neuroendocrine function)

Question 5

Bronchioles: what happens to
- Cartilage?
- Epithelial cell shape
- Cilia
- SMC

Answer 5

No cartilage
Become more cuboidal
Less
Less

Question 6

Are bronchioles physically supported by surrounding alveoli?
What happens to these attachments during emphysema/long term smoking and what is the consequence of this?

Answer 6

Yes - by bronchiolar-alveolar attachments
They’re lost, bronchioles are prone to narrowing and collapse especially during expiration

Question 7

Alveoli
TYpe I epithelial cells:
- Describe cytoplasm
- What percentage of SA?

Type II epithelial cells:
- What percentage of SA?
- What substance does it secrete - and what is the composition o fhtis substance? What is the role of this?
- Can these cells be progenitors for both type I and II cels?

Are there alveolar macrophages?

Answer 7

Very thin
90%

10%
Surfactant - 90% lipid, 10% protein. Reduce surface tension/lung collapse
Yes

Yes

Question 8

Blood gas barrier: describe the barriers gases need to pass to get from the air to the blood

Answer 8

air –> surfactant –> type I pneumocyte –> basement membrane –> endothelium –> plasma –> RBC (where O2 binds)