What is an example of the local barrier of the respiratory tract against infection?
Bronchus associated lymphoid tissue
Describe the two layers of fluid surrounding and above the cilia.
Watery periciliary fluid
Mucus (thick and gel-like)
What structures knit the epithelia into a cohesive layer?
How fast does each cilium beat?
15 times per second
Describe how the cilium is withdrawn after the forward stroke.
It is withdrawn in a curved fashion within the periciliary fluid and under the mucus so that it doesn’t pull the mucus back in the opposite direction.
Describe the rhythm of the cilia.
Describe the ultrastructure of the cilium.
It has a 9+2 structure - it has 9 microtubule pairs around the outside and two microtubules in the middle
The outer microtubule pairs have inner and outer dynein arms
What enables the cilia to move?
ATPase on the dynein arms
If a patient has recurrent chest infections, where could the problem be?
It could be a bad infection itself
But it could also be a problem with the host defence
Give two examples of acquired defects of the mucociliary system.
Why do bacterial infections often follow viral infections?
Viruses can damage the epithelia allowing the bacteria to dock down and colonise
What can happen to the cilia when they grow back?
They can regrow abnormally and form compound cilia, which are useless
What is the relationship between cilia and dextrocardia?
50% of people born without functioning cilia have dextrocardia
This is because the microtubules are involved in guiding cells around during embryological development.
What is the term given for congenital disease causing malfunctioning cilia? How does this disease affect the ultrastructure of the cilium?
Primary ciliary dyskinesia - this is caused by a dynein arm defect
What biochemical marker is used to assess risk of primary ciliary dyskinesia before performing nasal biopsy?
People with primary ciliary dyskinesia have lower levels of nasal nitric oxide than people without.
What is the most common cause of bronchitis and sinusitis?
What parts of the epithelium does bacteria stick to?
Damaged areas of epithelium - they do not stick to the ciliated epithelium