How does the kidney produce dilute urine?
Cl- is actively transported from the ascending loop.
Na+ is actively transported from the distal tubule.
absence of ADH
, the ascending loop, distal tubule, and collecting
ducts are impermeable to water, and so water does not
follow the Na+ and Cl- ions. The result is dilute urine.
How does the kidney produce concentrated urine?
Cl- is actively transported from the ascending loop into
the renal medulla (Na+ follows passively). The counter-current system of the loop
and the vasa recta blood vessels allows the build up of
high osmotic pressures. In the
presence of ADH
collecting ducts are permeable to water, and so water
is reabsorbed by means of osmosis. The result is concentrated