• Question: While we are alive on Earth, why doesn't gravity pull our blood to our feet?

    Asked by wizzyg12 to Claire, Kate, Matt, Rob, Sam on 19 Jun 2013.
    • Photo: Sam Geen

      Sam Geen answered on 19 Jun 2013:

      It does, some, but the heart pumping blood around our body is stronger than gravity. Occasionally when people get old gravity pulls fluid to their feet, called edema or oedema, causing their feet to swell up a bit. But this doesn’t affect the blood, I don’t think.

    • Photo: Robert Woolfson

      Robert Woolfson answered on 19 Jun 2013:

      Basically, the heart is stronger than gravity so while we’re alive the heart pushes the blood around the body. The heart is so strong that if you cut an artery the blood can travel a couple of metres (I think) from the force of the pumping.

      When we die, this stops and so all the blood pools in areas at the bottom of the body. This is how coroners can tell if people have been moved after they died.

    • Photo: Matthew Pankhurst

      Matthew Pankhurst answered on 19 Jun 2013:

      Great question -our bodies are constantly fighting gravity because it wants to pull us down and we want to be free to get on with our lives! The heart is a pump which squeeze blood around, up down, and sideways through our bodies, which takes a lot of energy, which means it doesn’t all drain to our feet. However, gravity isn’t all bad – if it wasn’t for gravity our bones wouldn’t be a strong, and we wouldn’t have much muscle. This is why astronauts who live at zero gravity have to work out a lot to keep in shape – because if they don’t, their muscles sort of give up and disappear gradually 🙂

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