The life expectancy of the cell
The lifespans of different cells vary greatly
Cells can last a human lifetime, but not many do. Some, such as the white blood cells that hunt down bacteria, are gone in less than a day, while cells in the lining of the gut hang around for nearly a week. Most, though, last a good deal longer – liver cells for a year or so, bone cells for perhaps ten years.
Just a few kinds of cell can endure from birth to their owner’s death. They include cells inside the lens of the eye (which become inert once they are in place in the embryo), cells in heart muscle and, perhaps most importantly, neurons in the brain.
Counting all the cells a person ever has would take several lifetimes. The average turnover of all human cells in different tissues is seven to ten years, so the lifetime cell count is perhaps ten times the adult total – at least several tens of trillions of cells. That ignores many other cells, like the 180 or so types of bacteria and other microorganisms that live in and on our bodies. This microbiota has a significant impact on human health, and it’s thought that each of us carries ten times as many of these cells as we have our own, human cells, which can account for 3 per cent of our body mass.Lead image:
Adapted from Glyn Nelson/Flickr CC BY NC