• Question: How many cells do we have in our bodies?

    Asked by cmur1889 to Tomasz, Matt, Dave, Aoife, Anzy on 19 Nov 2013.
    • Photo: Aoife O'Shaughnessy-Kirwan

      Aoife O'Shaughnessy-Kirwan answered on 19 Nov 2013:

      Hi cmur1889,
      There are trillions of cells on our bodies. I think the current estimate is somewhere around 50 trillion. Pretty cool huh? : )

    • Photo: Matthew Tomlinson

      Matthew Tomlinson answered on 19 Nov 2013:

      I think it’s a bit lower at around 10 trillion, although there are also about 90 trillion bacteria in our bodies!

    • Photo: David Christensen

      David Christensen answered on 19 Nov 2013:

      I don’t think scientists really know how many cells we have, but I’ve heard an estimate between Aoife’s and Matt’s. I’ve heard 37 trillion.

      I read something about this recently that was really interesting. Here’s a link: http://phenomena.nationalgeographic.com/2013/10/23/how-many-cells-are-in-your-body/

      I’ll give a quick summary of some of what is written in that though.

      The problem is that it is not really possible to count the number of cells so we have to try to find a good way to estimate it.

      One way is by thinking about how much a cell weighs. On average a cell weighs 1 nanogram. An average adult man weighs 70 kilograms. That means that a man might have 70 trillion cells.

      Another way to calculate is by thinking about volume. A mammalian cell takes up about 4 billionths of a cubic centimetre (very small!). Based on the size of an adult man, you might think that we have about 15 trillion cells in us. There’s a big difference between 70 trillion and 15 trillion!

      Or you can try to divide the body up into different parts and work out how many cells are in each organ. Apparently there are about 50 billion fat cells and 2 billion heart muscle cells. If you add these and everything else together (not including all the bacteria) you get about 37 trillion.

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