Nugget of Knowledge: Exchange of cells in a lifetime

Water in the body is recycled regularly

YOUNGSTOWN, Ohio (WYTV) – Are we the same person that we were say, five years ago?

You may have heard that we replace every cell in our bodies every few years, but that’s not correct.

We do replace our fat cells at the rate of 10 percent a year, so after 10 years, every fat cell is different. But heart muscle cells turn over at just 1 percent per year at age 25, going down to just half a percent by age 70.

So even if you live to be 100, you’ll still have more than half of the heart muscle cells you were born with.

Are there some cells that never change?

Yes, The neurons in your cerebral cortex and the cells in the lens of your eye are never replaced. You’ve got the same ones from birth, as well as the same with the calcium in your teeth — it’s locked up forever.

If a cell isn’t exactly replaced, it does change?

It exchanges molecules with the environment. The water in your body, for example, turns over at about 3 quarts a day. An adult has around 40 quarts of body water, so that’s 7.5 percent per day.

After two years, it’s statistically unlikely that you have any of the same water molecules.

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