The human body produces waste products that could be harmful if they were not excreted. The body also needs to maintain the volume of water and the concentration of dissolved substances in the blood. The excretory system functions to maintain homeostasis in the body by removing waste and returning substances that the body needs from the blood.

In this lesson, you will explore the following questions:

• What are the principal structures of the excretory system, and how do they function?

• How do nephrons contribute to the function of the excretory system?