Sample of human<unk> <unk>  is a liquid by-product of metabolism in humans and in many other animals.<unk>  flows from the kidneys through the<unk> eters to the<unk> ry bladder.<unk> tion results in<unk>  being excreted from the body through the<unk> ethra. Cellular metabolism generates many by-products that are rich in nitrogen and must be cleared from the bloodstream, such as<unk> ea,<unk> ic acid, and creatinine. These by-products are expelled from the body during<unk> tion, which is the primary method for excreting water-soluble chemicals from the body. A<unk> lysis can detect nitrogenous wastes of the mammalian body.<unk>  plays an important role in the earth's nitrogen cycle. In balanced ecosystems,<unk>  fertilizes the soil and thus helps plants to grow. Therefore,<unk>  can be used as a fertilizer. Some animals use it to mark their territories. Historically, aged or fermented<unk>  (known as lant) was also used for gunpowder production, household cleaning, tanning of leather and dyeing of textiles. Human<unk>  and feces are collectively referred to as human waste or human excreta, and are managed via sanitation systems. Livestock<unk>  and feces also require proper management if the livestock population density is high.
Urine
Serum 
Blood
Feces
Body fluid
Urinal 
Blood plasma
Venom