The following is a question from 2013's Medicine entrance exam (Belgium), Biology.

We look at the effect of antidiuretic hormone (ADH) on the concentration of uric acid of blood and on the osmolarity in blood. Furthermore, we look at whether an increased intake of salt has a similar or opposite effect.
Which of these rows is correct?

A: ADH increases: concentration of uric acid increases/ ADH increases: osmolarity increases/ Effect of increasing salt intake is: opposite
B: ADH increases: concentration of uric acid increases/ ADH increases: osmolarity decreases/ Effect of increasing salt intake is: similar
C: ADH increases: concentration of uric acid decreases/ ADH increases: osmolarity increases/ Effect of increasing salt intake is: similar
D: ADH increases: concentration of uric acid decreases/ ADH increases: osmolarity decreases/ Effect of increasing salt intake is: opposite



My attempt:


I know that B is correct (according to the exam), however, I can't explain to myself why an increased intake of salt would have a similar effect. I think that an increased intake of salt will result in an increase of osmolarity. The uric concentration will (at first) decrease and ADH will increase to go back to homeostasis. Only after this process will the increased ADH lead to a decreased osmolarity, but the initial effect of increased salt intake should be opposite to that of an increased ADH level?

Help t.t

Yes

this

I can see that you still "need" some posts having joined on June 10, 2017, but this isn't the best way to obtain them :/

Anti-Diuretics cause water retention to occur. Same solute amount with increased solvent amount will lead to decreased osmolarity. In this situation, think of increased salt concentration similarly to, but not exactly, an anti-diuretic. My physiology is a little rusty, but I'd suggest you look at the nephron. Look at what happens at the proximal and distal convoluted tubes and the loop of Henle (as it pertains to ion exchange). This might be able to explain why B is the correct answer. Hope this helps.