Together with the skin and the respiratory
system, the kidneys are the body's primary excretory organs. The
kidney is a highly specialized organ that maintains the internal
environment of the body by selectively excreting or retaining
various substances according to specific body needs. The
importance of urine formation and excretion as a life-sustaining
function is highlighted in situations in which kidney function is
suddenly lost. Without at least one functioning kidney, death can
occur within a few days. This web page uses frames, but your browser doesn't support them.