The chemical structure of<unk> ea Most animals have excretory systems for elimination of soluble toxic wastes. In humans, soluble wastes are excreted primarily by the<unk> ry system and, to a lesser extent in terms of<unk> ea, removed by perspiration. The<unk> ry system consists of the kidneys,<unk> eters,<unk> ry bladder, and<unk> ethra. The system produces<unk>  by a process of filtration, reabsorption, and tubular secretion. The kidneys extract the soluble wastes from the bloodstream, as well as excess water, sugars, and a variety of other compounds. The resulting<unk>  contains high concentrations of<unk> ea and other substances, including toxins.<unk>  flows from the kidneys through the<unk> eter, bladder, and finally the<unk> ethra before passing from the body. Duration Research looking at the duration of<unk> tion in a range of mammal species found that nine larger species<unk> ted for 21 ± 13 seconds irrespective of body size. Smaller species, including rodents and bats, cannot produce steady streams of<unk>  and instead<unk> te with a series of drops.
Urine
Serum 
Blood
Feces
Body fluid
Urinal 
Blood plasma
Venom