milu
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An obstruction in the proximal convulated tubule decreases glomerular filtration rate because:
a) Blood hydrostatic pressure in the glomerular decreases when blood can't flow through the tubule.
b) osmotic pressure in the glomerular capsule increases due to leakage or more proteins into the filtrate
c) hydrostatic pressure in the glomerular capsule increases, which decreases net filtration pressure.
d) hydrostatic pressure in the glomerular capsule decreases due to leakage of more filtrate into the peritubular space
e) release of renin decreases as fluid flow to the macula densa decreases.
EXPLAIN IT PLEASE..
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| anne
Forum Elite
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ans=c
obstruction of proximal tubule would lead to outflow obstruction of GFR.but the glomeruli keep doing their task of filtering plasma.so there's buildup of filtrate in prox.tubule,leading to increased hydrostatic pressure in bowmann's capsule,which would oppose filtration.so GFR would decrease.
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| dxtxpx
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i dont understand: According to BRS physio 2nd ed, pg 161:
'Glomerular capillary hydrostatic pressure is normally constant along the lenght of the capillary. It is increased by dilation of afferent arteriolar or constriction of efferent arteriole. Increases in Glomerular capillary hydrostatic pressure increases in net ultrafiltration pressure and GFR
plz explain
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| mdwannabe
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what it says is TRUE. But obstruction of PCT has nothing to do with Glomer. Capil. it affects GFR secondarily as the pressure in Bowman's space goes up. Just look at any graph, in any Phisio book, that shows Starling forces as applied to Glomerulus.
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| dxtxpx
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thanks i was bit confused bout the question. thanks
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| mdwannabe
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pay attention to wording... INCREASE IN GLOMER. CAP. Hydr. Stat. Pressure... not same as INCREASE in BOWMAN's space Hydr. Stat. pressure. These two oppose each other, with GLOM. Cap. HP usually winning the battle by a couple of mm of Hg.
Any obstruction to PCT or any other tube , will increse Bowman's space HP and so pressures between Glom. Cap HP and Bowman's space HP will be more equal, hence reducing potential for ultrafiltrate to leave capilary space... that is DECREASED GFR.
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| dxtxpx
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ok now i am more confused :shock: BRS use the word glomerular not bowman's space. I will state again from BRS pg 161
Increase in glomerular capillary hydrostatic pressure causes increase in net ultrafiltration pressure and GFR
Increase in bowman's space hydrostatic pressure decreases in net ultrafiltration pressure and GFR
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| mdwannabe
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Again you just restated same thing I tried to explain above.. you have it! Be confident! If you have some concerns write a private message, I ll try to exlpain it that way.
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| dxtxpx
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yeah sorry for the trouble, i re-read the whole topic and i do get it now, i didnt see glomerular capsule and kept thinking in my head that it says glomerular capillary so thats y the whole confusion. :oops:
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