The human body is self-repairing and self-replenishing. According to one estimate, almost 200 billion cells die each hour. In a healthy body, dying cells are simultaneously replaced by new cells.
Cell Type |
Length of Time |
Red blood cells |
120 days |
Lymphocytes |
Over 1 year |
Other white blood cells |
10 hours |
Platelets |
10 days |
Bone cells |
25–30 years |
Brain cells* |
Lifetime |
Colon cells |
3–4 days |
Liver cells |
500 days |
Skin cells |
19–34 days |
Spermatozoa |
2–3 days |
Stomach cells |
2 days |
*Brain cells are the only cells that do not divide further during a person’s lifetime. They either last the entire lifetime or, if a cell in the nervous system dies, it is not replaced.