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Qestion, - balu
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06-01-2007, 11:54 AM
6 year old caucsian boy w/ recurrent otitis media and sinusitis is found to have a higher then normal nasal transepithelial potential difference. Wich of the following processes moste likely underlines this finding?
a.increased Cl secretion b.increased Na secretion c.intracelular K depletion d.high mucous water contant.
06-01-2007, 12:20 PM
Answer is B, Dx. of CF is usually based on increased sweat Cl concentration, however, a small portion of pts w/ CF ispecially those w/ a "mild" mutation of CFTR have near normal sweat test.
In CF abnormalities of CFTR transmembrane protein reduce ductal epithelial Cl concentration and increse Na and net waret reabsorbtion, result in dehydrated mucouse and widened transepithelial potential difference.
06-01-2007, 12:28 PM
if it s increased Na reabsorption in CF,howcome answer is B which is increased Na secretion?
06-01-2007, 12:35 PM
normal function of CFTR is promoting Cl secretion nd inhibiting Na resorption.
when mutation occurs,Na is secreted,so in CF,increased Na secretion . |
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