> Skin: The epidermis sees a fair amount of wear and tear, thanks to its role as the body's outermost layer of protection. These skin cells rejuvenate every two to four weeks.
Hair: The body's natural fuzz has a life span of about six years for women and three years for men.
Liver: The liver is the human body's detoxifier, purifying a wide variety of contaminants from our systems. It's aided in the process by a constant blood supply and remains largely immune to damage from these toxins by renewing itself with new cells every 150 to 500 days.