Nephron.

A nephron is a structure inside the kidney that helps filter waste from blood. Each kidney in the human body contains approximately one million nephrons. Each nephron is made up of three main parts—a renal corpuscle, a renal tubule, and a capillary network. These parts filter waste from the blood, reabsorb water into the blood, and help move the final waste product out of the kidneys. Nephrons are the main function units of the kidneys and are vital to renal function.