What organs perform the excretory function in the human body and what substances do they excrete?

1) lungs – through them carbon dioxide, water vapor are removed from the human body;
2) sweat glands of the skin – water, salts and a small amount of urea are removed through them;
3) kidneys – through them, the final products of protein metabolism (urea), excess water and mineral salts are removed;
4) the gastrointestinal tract – through it, excess water and substances disinfected in the liver are removed.