Functions of kidney:

1. Removes urea/uric acid from blood.
2. Maintains osmo-regulation (ion & water level of body fluids)
3. Filters the acidic substances from blood & maintains the PH oh blood to about 7.4.
4. Removes water like pigments, drugs, poisons & excess vitamins from body.
5. Maintains homeostasis (a fixed body temperature).
6. Regulates blood pressure by regulating water balance of body fluids.
7. Kidney releases renin, that is very important for Na⁺ re-absorption.