If every cell in your body is replaced roughly in 7 years, why do the affects of smoking and other bad habits still affect people who quit?

Question

If every cell in your body is replaced roughly in 7 years, why do the affects of smoking and other bad habits still affect people who quit?

In: Biology

Answer 1

Not every cell gets replaced 7 years, if accurate at all, is an average. Some cells may never be replaced (nervous system), some are replaced often (skin, blood, hair). The cells that are replaced are replicated from your existing cells so damage accumulates over time.