Flashcards in Respiration's First Defenses Deck (22):
Why do you need to be careful placing an NG tube in someone who's had sinus surgery?
The remaining bone is thin... and you could put the tube through the back of a sinus and into the brain.
When you have a cold and get "congested," what does that actually mean?
The turbinates swell.
(this tends to happen one side at a time - a mysterious process called the nasal cycle)
It's important to warm and humidify air breathed in.
Why is turbulence created by the turbinates good?
It encourages particulate matter to drop out in the mucus.
(It makes it easier to smell, too.)
Sniffing directs more air flow toward the olfactory bulbs.
That makes sense.
95% of pollen-sized particles are deposited in the anterior nasal cavity.
(but only 60% of 2 micron particles are trapped)
(smaller stuff gets deeper into lungs)
Do we know what the paranasal sinuses are actually for?
They might lighten the skull, add resonance to the voice, and/or provide a crumple zone...
2 layers of mucus?
Is the thickness variable?
Gel (mucus) and sol (aqueous).
The thickness of the mucus layer is variable, but the sol layer must be kept constant for cilia beating to work.
Does the cilia beat frequency vary?
It sure does. At the faster mucus is moving, the easier it is for it to move.
What's interesting about the direction in which cilia beat?
Why is this important?
They know what direction to beat... in the sinuses, eg. this is toward the opening in a defined pattern.
Making a hole at the bottom of a sinus won't help it drain. Rather, the existing hole should be enlarged.
Secretory IgA is important.
It protects against viruses and bacteria.
If deficient -> recurrent sinusitis.
What kind of defensins are secreted in the airway epithelia?
What do they do?
Direct antimicrobial activity by forming pores in bacteria.
How is lactoferrin microbicidal?
Inhibits microbial growth by sequestering iron.
Lysozyme is particularly good against what kind of bugs?
Gram-positive bacteria - as it breaks down peptidoglycan.
Do surfactants have antimicrobial activity?
Yes, the hydrophilic ones, SP-A and SP-D help pathogens get cleared.
Toll-like receptors... help bridge the innate -> adaptive response. Is this fast or slow compared to other aspects of innate immunity.
A patient has pseudomonas sinusitis, gets ABx, feels better for a while, and then relapses. The culture strain is still sensitive to the ABx. What's likely going on here?
The pseudomonas likely formed a biofilm that is both difficult for ABx to penetrate, and contains bacteria that are less metabolically active, and thus less susceptible to ABx.
(when someone in the ICU has a fever, all the hardware is pulled out for fear of biofilms)
What is quorum sensing?
What might this have to do with bitter taste receptors in the airway?
Quorum sensing - bacteria secrete molecules allowing them to determine how many of their pals are around, and if they should start making a biofilm.
Quorum sensing molecules may stimulate bitter taste receptors (perhaps most importantly, T2R38, stimulating increased ciliary motion (via Ca++ signaling).
What effect does NO (nitrous oxide) have intraceullarly and extracellularly in the airway?
Intracellular: promotes cilia beating.
(might be a downstream effect of bitter taste receptor T2R38 signaling)
Does variance in T2R38 affect outcomes after sinus surgery?
Yeah... people with bitter-tasting phenotypes (PAV) seem to be better able to prevent biofilms from forming vs. non-tasting (AVI).
Is irrigation with saline a good idea?