Comment:
In addition to excretion, kidneys also help in osmoregulation and maintenance of PH.

The kidney participates in whole body homeostasis, regulating acid-base balance, electrolytes concentrations, extra cellular fluid volume and regulation of blood pressure, it helps in the formation of urine and excrete a variety of waste products produced by metabolism. These include the nitrogenous wastes called "urea" from protein catabolism, as well as uric acid from nucleic acid metabolism. Thus, it helps in maintaining Osmoregulation in the body.