We just learned about the Loop of Henle.
Another part of the kidney is the Distal Convoluted Tubule, also called the DCT.
As the blood is cleaned up along from the Loop of Henle, it goes to the DCT where it helps control the amount of potassium, sodium, and calcium in the blood.
(from: wikipedia - distal convoluted tubule)
Kid Facts - Blast from the past: Concha