• Question: what chemical change happens in our body in the spit second that makes us go from being alive to dead?

    Asked by to Alan, Deepak, Francesca, Lilly, Nick on 18 Mar 2014. This question was also asked by .
    • Photo: Francesca Day

      Francesca Day answered on 18 Mar 2014:


      That’s an interesting question. Scientists now think of death as a process rather than a moment – it’s actually not easy to define precisely when someone is dead! When we die, the chemical processes that keep us alive (respiration, brain activity etc.) gradually stop, but there is no precise chemical change that defines the line between life and death.

    • Photo: Alan Fitzsimmons

      Alan Fitzsimmons answered on 18 Mar 2014:


      There’s no instant chemical change. But when we die, oxygen stops entering through our lungs and into our blood, and our heart stops beating and pushing that fresh oxygen-carrying blood through our bodies. When that happens our organs stop working and our cells start dying because they need the oxygen to work.

    • Photo: Nick Wright

      Nick Wright answered on 21 Mar 2014:


      That’s a good question! We don’t think its an instantaneous change, but sort of a shutting-down as our bodies power down. We die when our heart can’t transport oxygen through our blood to all the places in our body, particularly our brains, so when the human heart stops working we die shortly after. This is usually because all the different parts of our body that we need to work (brain, liver, lungs, muscles) don’t have any blood being fed to them so they can’t work.

      But all these components need to work together in unison like a team, so if one part shuts down the others shut down too. So for example if the heart keeps working (pumping blood around your body) but the lungs have stopped working (breathing in oxygen) then there won’t be any oxygen in the blood that our heart is trying to pump around our bodies and things will stop working.

      Human bodies are amazing things, they are made up of lots of small components, each of which has a simple task to do, but each of which relies on all the rest of the body working.

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