secretion

[ctizzle13498]

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Can someone explain this to me:

secretion=excreted-filtered

thanks!

 

[Suncrusher]

my best guess: rearrange it to excreted=filtered+secreted

total excretion = things that pass through the glomerulus's filter + things that didn't make it through the filter but are transported directly into the kidney tubules.

So if you take the total excretion and subtract what made it through the filter, you can tell how much had to be transported straight into the tubules?



and I'm not sure why reabsorption isn't accounted for in your formula

 

[jfgavina]

excreted=filtered+secreted-reabsorbed

 

[ctizzle13498]

great! thanks that makes sense guys! and one more thing....i was looking at the loop diuretic Ethacrynic acid. It says in first aid that it can be used to treat hyperuricemia but that it should never be used to treat gout. how does this make sense? I thought people with gout have hyperurecimia.

 

[Suncrusher]

I think ethacrynic acid actually decreases the relative excretion of uric acid, although it would increase the volume of urine excreted in general and therefore decrease the body's total uric acid load. But it would be causing a relative increase in uric acid concentration at the same time and cause urate crystals to precipitate, worsening the gout.

 

[Suncrusher]

Everyone who has gout has hyperuricemia, but not everyone who has hyperuricemia has gout. So if someone has hyperuricemia without gout, you can use ethacrynic acid to make them urinate more (even though less uric acid would be excreted per volume of urine) and eventually treat the hyperuricemia, although I can think of many drugs that would be a better choice to treat hyperuricemia than ethacrynic acid...probenecid is the best...

but for people whose hyperuricemia is causing gout, the relative increase in uric acid concentration is just going to precipitate more urate crystals and make the gout worse.

 

[Tig2575]

Filtration is solutes being filtered across the glomerular basement membrane

Reabsorption is solutes being transported from the nephron tubule back into the blood

Secretion is solutes being transported from the blood into the nephron tubule

Excretion is solutes inside the nephron tubule being washed out into the urine.