Weight is a good guideline for blood volume in people of average build. This is why we set a minimum weight limit of 7st 12lbs (50 kg) because if more than 13% of blood volume is taken there is more risk of the donor feeling faint after donating.
Not surprisingly, the one factlet most often offered up as revealed truth is wholly false: Your hair and nails do not continue to grow after you die; it's all optical illusion. The sorry fact of the matter is that we dehydrate after dying. Our flesh dries and, in so doing, pulls away from nails and hair.
Hair generally grows an average of 1/2 inch per month, with growth generally predetermined by a person's genetic code, meaning that it can only grow so fast. In a year, hair usually grows about 6 inches. As a person ages, hair growth can slow due to cell division also slowing. Hair growth is a result of cell division when new hair cells form in the root and push the hair forward. The new hair is always added at the root as the older hair inches downward slowly.