Asked in Human Anatomy and Physiology
Does your body change every seven years?
If you average all the cells as they live, multiply, and die, many sources say that it takes seven years for all of them to change in your body. This is somewhat true, but also somewhat misleading. The truth is that different cells have different lifespans. For example, the nerve cells in your brain do not multiply and they last for your entire life. If any of them die, they do not get replaced. At the other end of the spectrum are the white blood cells in your body. They have the shortest lifespan and some of them live only a few days.
So, in actuality, the concept that your body changes every seven years is not exactly true, because even though most of your body cells will have reproduced and replaced themselves, not all of them have, and some have replaced themselves many times over during those seven years.