Question

In the kidneys, the __(i)__ and the __(ii)__ mechanisms occur. The first takes place in a region of the nephron called __(iii)__; the second occurs in a region of the peritubular capillary bed called the ___(iv)___

• A. i-Counter-current multiplier, ii-Counter-current exchanger, iii-Henle's loop, iv-Vasa recta.
• B. i-Counter-current exchanger, ii-Counter-current multiplier, iii-Henle's loop, iv-Vasa recta.
• C. i-Counter-current multiplier, ii-Counter-current exchanger, iii-Vasa recta, iv-Henle's loop.
• D. i-Counter-current exchanger, ii-Counter-current multiplier, iii-Vasa recta, iv-Henle's loop.

Answer 1

The correct option is A

i-Counter-current multiplier, ii-Counter-current exchanger, iii-Henle's loop, iv-Vasa recta.

The mechanisms shown here are traditionally called the 'countercurrent multiplier' and the 'countercurrent exchanger'. The first takes place in a region of the nephron called Henle's loop; the second occurs in a region of the peritubular capillary bed called the 'Vasa recta'. Both are involved in establishing respective osmotic gradients throughout this region.