You may have heard that your body essentially regenerates every seven years, but, like many ideas traveling from person to person, it's not exactly that simple. The idea that your whole body is new every seven years is basically a myth, but many of the cells in your body do change over regularly. It's just that the different kinds of cells and different parts of the body change and regrow at different rates. The shocking ways your body changes about every few years might be interesting for you to know, particularly if you thought that it was true that your entire body changes every seven years.
Some of the cells in your body turnover every couple of days, others take weeks, months, or even years. Some may or may not really ever turn over. Researchers are still discovering the ways some of these things might work (or exploring how stem cells might change the way cells work). It seems that there are very few hard and fast rules about how rapidly your body changes this way. In a video, Brain Stuff noted that your body generally renews over the course of seven to 15 years, but clarified that the different parts of your body take different lengths of time to replace themselves. There are different things changing all the time. If you're interested in which body tissues turn over every few years, here's what you need to know.
1. Men's Hair Changes About Every Three Years
Men's hair tends to change about every three years, HowStuffWorks noted. The hair growth cycle has a number of different stages and there are a number of things that can affect the fullness of your hair. You may have noticed that it thins a bit as you age or that you lose some more when you get especially stressed. There are a lot of different factors that can cause hair growth and the like to vary.
2. Your Liver Can Renew Every Few Years
The previously-mentioned video from Brain Stuff noted that your liver typically turns over every couple of years, though the exact amount of time that it takes can vary. PubMed Health noted that the liver is extremely important when it comes to removing not-so-healthy things from your body. It certainly serves an important purpose — and can even regenerate from a small piece of an organ to a larger, more full-sized organ, which is why living donors can donate parts of their livers to others, as Columbia University's department of surgery noted.
3. Your Hair Changes Every Two To Seven Years
A video from NPR's Skunk Bear said that the hair on your scalp can take between two and seven years to change over and that you lose about 100 strands each day. You probably already know that you lose hair regularly and that, typically, more grows in where it used to be, but you might not realize that the entire process, in which all of the hair on your head has turned over, can take multiple years. It might actually be a longer process than you thought.
4. Heart Endothelial Cells Turnover Every Six Years
Though scientists are still exploring and examining whether or not your heart muscle cells and the neurons in your brain can be regenerated (and it might potentially be possible that both can, at least, to a certain extent), your heart's endothelial cells, the cells that line your heart (endothelial cells also like your blood vessels of all sizes) do, in fact, turn over. Business Insider reported that heart endothelial cells, on average, turn over every six years or so.
The cells in your body work hard each and every day, which is why some of them have to turn over so quickly. Even those cells that don't regenerate as quickly or in the same way are hard at work going through all of the processes that your body needs in order to function and do all of the things that you need to do. Knowing which cells turn over at which rates doesn't necessarily have a huge impact on your day-to-day life, but it does help you learn more about your own body and how it works — beyond what you may have learned in a high school science class.