• Question: Why do we urinate

    Asked by princesselliecertifiedlightskin to Mona, Joseph, Jen, Emma on 14 Jun 2011. This question was also asked by siimpleetee.
    • Photo: Joseph Finlayson

      Joseph Finlayson answered on 14 Jun 2011:

      Our kidneys filter out waste products that our bodies produce, as well as excess salt. The main waste component that is removed urea (which makes urine yellow), this is produced by the liver when it breaks down protein to create energy.

      Too much of these waste chemicals and too much salt can be toxic, so in our kidneys they are forced out of the blood into a thin tube that leads to our bladder. When our bladder is nearly full, we go to the toilet and release it.

      Hope that helps!

    • Photo: Jen Gupta

      Jen Gupta answered on 14 Jun 2011:

      I think Joseph’s covered this pretty well although I guess we also urinate because our bodies only need so much of the water that we drink so if we drink too much then we have to get rid of it somehow!

Comments

  • Photo: Joseph

    Joseph commented on :

    Interestingly, we only drink the amount of water that we do drink because our kidneys are so inefficient. They can only excrete the waste substances to a maximum concentration, so we need a large amount of water to allow our urine to be excreted by our kidneys.

    Some birds on the other hand, have very efficient kidneys, when they ‘poo’ they are actually excreting very concentrated urine – or even urine crystals (crystals of uric acid, to be precise). If our kidneys had evolved to be as efficient as birds’ we’d actually drink a lot less water than we do – perhaps as little as a cup per day.