If all human cells replace themselves every 7 years, why can scars remain on you body your entire life?

Question

If all human cells replace themselves every 7 years, why can scars remain on you body your entire life?

In: Biology

Answer 1

The cells replace those cells that die. The new cells take the place of the dead cell. Since the old cell was a scar cell the new cell will also be a scar cell. The new cells therefore form the scar just like the old cells did. It only gets a tiny bit smaller over time as the scar cells at the outermost edges might get replaced by the proper skin cell instead of a new scar cell. In addition the 7 years is an average for how long our cells last. Some cells are replaced every few weeks and some are never replaced.