another question about the kidney

[Pamplemousse123]

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long loops of henle on juxtamedulalry nephrons allow for greater concentration of urine. for an individual with highly conceentrated urine, filtrate enetering the loop of henle is likely to be:

a. more concentrated than filtrate exiting loop of henle
b. less concentrated than filtrate exiting loop of henle
c. more voluminous than filtrate exiting loop of henle
d. less voluminous than filtrate exiting loop of henle

i thought it was B because if you have a greater concentration exiting loop of henle, it makes sense that you would have a greater concentration of urine. but answer is a. can someone explain why it is a...and also why should volume not have anything to do with it (why d is incorrect as well). thanks!

 

[thestrokes14]

long loops of henle on juxtamedulalry nephrons allow for greater concentration of urine. for an individual with highly conceentrated urine, filtrate enetering the loop of henle is likely to be:

a. more concentrated than filtrate exiting loop of henle
b. less concentrated than filtrate exiting loop of henle
c. more voluminous than filtrate exiting loop of henle
d. less voluminous than filtrate exiting loop of henle

i thought it was B because if you have a greater concentration exiting loop of henle, it makes sense that you would have a greater concentration of urine. but answer is a. can someone explain why it is a...and also why should volume not have anything to do with it (why d is incorrect as well). thanks!

It is the countercurrent multiplier system you were talking about. The ascending loop of Henle is impermeable to water, but expends energy to force ions out (decreasing the concentration of the urine). The descending loop of Henle, which is prior to the ascending, loses water, but no ions, by osmosis as a result. This makes the urine very concentrated. I am not sure how you compare volume though.

 

[Pamplemousse123]

Thanks! I understand it now!