1. Removal of metabolic waste products: This includes substances like urea (from protein breakdown), creatinine (from muscle breakdown), and excess water and salts. These waste products are harmful to the body if they build up, so the excretory system filters them out of the blood and eliminates them from the body.

2. Regulation of blood volume and composition: The excretory system helps maintain the proper balance of water, electrolytes (like sodium and potassium), and other substances in the blood. This ensures proper blood pressure, cell function, and overall body homeostasis.