Functions of kidney :

1. Excretion : Kidneys pass out metabolic waste products.

2. Regulation of pH value : Kidneys help in the removal of excess of acids from the blood and thus help in regulating pH value.

3. Osmoregulation : Kidneys help in the maintenance of the osmotic balance in the body.

4. Secretion of renin : The kidneys secrete renin which converts angiotensinogen into angiotensin. It stimulates the limbs of uriniferous tubules to absorb Na⁺ ions from blood.

5. Elimination of excess of salts : The kidneys elminate excess of salts from blood and thus help in regulating blood pressure.

6. Regulation of blood pressure : By controlling the fluid balance in the body, kidney nephron regulates blood pressure.

7. Homeostasis : As kidney removes various unwanted material from the blood, it helps in keeping the internal environment of the body constant.

8. Elimination of other substances : Kidney removes toxic substances like drugs, pigments etc. from the blood.