RESP-lung defence Flashcards
what is the mucociliary escalator?
the structures that waft pathogens/foreign bodies out of the large airways
what is the mucociliary escalator made up of?
- lined by respiratory epithelium
- cilia
- ASL
- gel layer
which type of epithelium lines the large airways of the respiratory system?
pseudostratified ciliated columnar epithelium (+ goblet cells)
what is the role of cilia?
beat in a coordinated manner to push pathogens out of lungs (sol layer)
what is the role of ASL in the mucociliary escalator?
combined with cilia to make up sol layer of mucociliary escalator
what is the role of gel layer in the mucociliary escalator?
contains mucins (glycopeptides) which make up mucous
how does the mucociliary escalator work?
cilia wafts pathogens which travel and stick inside mucous up to throat, where they can be coughed out or swallowed and destroyed by stomach acid
at what height must the sol layer remain at?
same height as cilia->7um
what happens of the sol layer is too thick?
cilia won’t reach top of liquid to push pathogens along
what happens of the sol layer is too thin?
cilia squashed –> unable to beat all together
how is the height of the ASL maintained?
through Na+ transport
what is the response to too much water in the ASL?
- ENaC transports Na+ out of ASL and into epithelial cell. The Na+ is then removed on the basolateral side by an Na+/K+ pump Via blood
- Water follows
what is the response to too little water in the ASL?
- CFTR channels downregulate ENaC channels prevents Na+ (and water) leaving ASL
- CFTR channels also pump Cl- ions out of epithelial
cell into ASL – this attracts water
what type of condition is CF?
Autosomal recessive condition
what causes CF?
-Mutated CFTR channel
what is the result of mutated CFTR channel in CF?
- NO downregulation of ENaC and Cl- ions cannot be pumped into ASL to attract water
- ENaC now moves Na+ and water out of ASL uninhibited –> thick, stagnant mucous that houses pathogens in an ideal reproductive environment
- Cilia cannot reach top of sol layer-also cannot move efficiently inside thick mucous
name the 3 types of immune defence in the airways.
- innate defences (alveolar macrophage which phagocytose pathogens)
- adaptive defences (immunoglobulins)
- mucociliary escalator = physical defence
what is the most common pathogen seen in CF?
pseudomonas aeruginosa (gram negative)
what occurs in CF once the airways are infected?
-airways carry out an intense inflammatory neutrophil-mediated immune response
what occurs do to leukocytes getting trapped in the mucus in CF?
- leukocytes trapped in thick mucus begin to destroy the airways
- begins a downward spiral of cytokines, proteases and even chondrolysis (break down of cartilage)
what is the result of the inflammation in the airways seen in CF pateints?
- does a lot of damage to the person’s airways, and people with cystic fibrosis have very scarred airways
- long-term result is bronchiectasis and repeated infections-eventually, respiratory failure
what is the role of IgA in lung defence?
Primarily functions through blocking adhesion + airway secretions
where is IgA found?
in circulation
what is the role of IgG in lung defence?
-Primarily functions through opsonisation
