The kidneys produce urine and this helps maintain water balance. The urine is taken from ... until it is convenient to expel it from the body. Note that 'ureter' differs from the word 'urethra'.

The kidneys are organs of the urinary system - which remove excess water, mineral ions ... blood plasma as many ions as the body needs to maintain a constant balance of mineral ions in the blood ...

"Whether people are athletes or not, the human body is constantly losing water through normal human functions" ...