• Question: how many cells will a human go through in a lifetime!

    Asked by josephwozniak to Dave, Matt, Tomasz on 21 Nov 2013.
    • Photo: Matthew Tomlinson

      Matthew Tomlinson answered on 21 Nov 2013:


      Lots and lots and lots! If you look just at red blood cells, which live about 120 days, and are made at a rate of 2.4 million per second(!), then in a lifetime of 80 years (which I think will be seen as short in the near future) then a person will go through make about 6,054,912,000,000,000 or 6.054912 quadrillion red blood cells cells! So if you look at the whole body, which contains about 30 trillion cells, then you have to be looking at septillions of cells at least (10 with 24 zeroes after it!).

      That is a lot of cells!

    • Photo: David Christensen

      David Christensen answered on 21 Nov 2013:


      That’s a difficult question, but I can try to give a rough guess!

      Apparently about 50 billion cells die and are replaced every day in the average adult. That means we go through about 18 trillion cells each year. These numbers will be less during childhood because we’re smaller and then made up of fewer cells, but this is just a rough guess anyway. If we work with the rough life expectancy of 80, then we will go through 1,460,000,000,000,000 cells in our life times – that is 1.46 quadrillion cells!

      The average adult is made up of about 40 trillion cells (as a rough guess). This would then suggest that we remake ourselves about 35 times through our lives. This isn’t actually really true because some cell types die and are replaced a lot faster than others – particularly red blood cells where apparently 2.4 million are made every second!

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