lecture 4: structure and function of the airways Flashcards
what are the basic functions of the airways?
- conduit to conduct oxygen to the alveoli and the co2 out of the lungs
- they are needed to facilitate mechanical stability
- control calibre
- protect and clean mucus
what is the basic anatomy of the airways and lungs?
- the branching of the lungs is called dichotomous branching
- the c rings of the bronchi and trachea are slightly offset from eachother to give greater tensile strength
** what is the organisation of the airways?
- the c rings are not complete
- the c rings are offset
- below the cartilage there is a layer of smooth muscle
- submucosal glands are embedded
how doe the cilia beat?
- metasynchronously
how much mucus is made a day ?
what cells make the mucus ?
how do the goblet cells secrete their mucus?
10mL
goblet and submucosal glands
- mucin granules come to the apical surface and fuse with it
- a little pore forms and water goes through the pore
- the concentrated mucus expands rapidly
- then the mucus pops out
- a massive amount of mucin comes out of a tiny granule
***what is the function of the airways epithelia?
- secretion of mucin, water and electrolytes
- movement of mucus by cilia
- physical barrier against inhaled insult
- production of regulatory and inflammatory mediators
NO
CO
chemokines
cytokines
***what is the arrangement of the airway submucosal glands?
- functioning areas are called acini
- they secrete mucus out of the collecting duct
- the mucus moves to the collecting duct
- the cilia waft the mucus
- there are serous glands that are peripheral to the mucus cells
- the serous cells make watery mucus
- the watery secretions from the serous cells flush over the mucus secretions
- the glands also secrete water and antibacterials ect.
what is the function of airway submucosal glands?
- mucous cells secrete the mucus
- serous cells secrete anti bacterials
- glands also secrete water and salts
what is the structure of cillary?
Each individual cilia displays a ‘9+2’ relationship with 9 filaments around 2 central filaments.
The rods then slide over each other to simulate movement.
200 cilia per cell.
how do the cilia beat?
metachronal rhythm
like a wave
cilia waft the mucous up the respiratory tract using the apical hooks
what is the smooth muscle function in the airway?
regulates
tone
secretion
structure
what happens to the smooth muscle function during respiratory disease?
With respiratory disease, more inflammation and smooth muscle hypertrophy/proliferation which increases contractile forces of smooth muscle meaning more secretions are made
furthermore
in response to cytokines NOS is up regulated
- in response to chemokines inflammatory cells are recruited
- the COX enzymes produce more prostaglandins
what does the tracheo bronchial circulation do?
- takes 1-5% of cardiac output
- blood flow to the airway mucosa
- very rich in blood so you get direct gas exchange
- contributes to the warming and humidification of inspired air
- clears the inflammatory mediators and inhaled drugs
- Supplies airway tissue and lumen with inflammatory cells and proteinaceous plasma
***what is the mechanism of plasma exudation in the airways
- When the endothelial cells contract, they pull away from each other and form a gap which plasma leaks from
- This system can become exaggerated in disease
- endothelial cells are served by sensory nerves
- so in something like asthma these sensory nerves might become activated and therefore causing the plasma exudation process
what are the control systems of airways function?
- the nerves are PNS and SNS
- the regulatory mechanisms are
- histamines
- cytokines and chemokines
- Arachidonic Metabolites.
- proteinases
- reactive gas species
NO is important
