Structure and function of the airway* Flashcards
What shape is the cartilage in the trachea?
C shape, doesnt go all the way round
Why is there no cartilage at the back of the trachea?
So food can go down the oesophagus which is attached to the back of the trachea
What is the branching in the airways called?
Dichotomous branching- 2 to 2 to 2 (doubles)
What type of stability does cartilage provide?
Mechanical stability
Where does gas exchange occur?
Alveolar region
How many macrophages are there in an alveolus?
2 or 3
What do fibroblasts in the alveolar unit produce?
The matrix that the alveoli are contained
Why are type 1 cells good for providing the barrier for gas exchange?
They are very thin- short diffusion distance
What do type 2 cells do?
Replicate the produce type one cells
Secrete surfactant
What percentage do type 1 and type 2 cells cover alveolar surface?
Type 1- 95%
Type 2- 5%
What shape are type 1 cells?
Fried egg shape
What does the calibre of the airway mean?
How open or closed it is
What controls the calibre of the airway
Smooth muscle
What are the conchae?
Shelves of bone in the nasal pathway
Why do the conchae need to be highly vascular?
To contribute to warming and humidification of air so it doesn’t damage the delicate thin type one cells
Why are nasal hairs in the conchae important?
To filter out large particles
What is the pharynx?
A common passageway for liquids, food, and air
What is the structure of a cross section of the airway wall (innermost to outermost layer)?
airway lumen, mucus, cillia, epithelial lining and goblet cells, submucosal glands smooth muscle and blood vessels, cartilidge
What is mucociliary transport?
Mucus traps particles and cilia waft that mucus to the back of the throat
Why are there a lot of mitochondria around cilia?
Because a lot of mitochondria is required for them to beat all the time
What are the 2 types of acini in airway submucosal glands?
Mucus acini and serous acini
What do serous cells secrete?
Antibacterial enzymes
Describe the transverse section of a cilia.
9 pairs of things in a circle with two in the middle
What are the 4 functions of airway epithelium?
- Secretion of mucins, water and electrolytes
- Movement of mucus by cilia – mucociliary clearance
- Physical barrier
- Production of regulatory and inflammatory mediators
Name 6 regulatory and inflammatory mediators produced by the airway epithelium
Nitric oxide (NO - via nitric oxide synthase, NOS)
Carbon monoxide (CO - via hemeoxygenase, HO)
Arachidonic acid metabolites (e.g. prostaglandins – via COX)
Chemokines (e.g. interleukin (IL)-8)
Cytokines (e.g. GM-CSF)
Proteases
