Although you may think of your body as a fairly permanent structure, most of it is in a state of constant flux, as old cells are discarded and new ones generated in their place. Each type of tissue has its own turnover time, depending in part on the workload endured by its cells.
Adult stem cells are at the core of your body's natural renewal system; 50 to 70 million cells are discarded and replaced daily.
The Human Body Is in a State of Constant Flux