86 Nanomedicine every tissue cell of your body (requiring a total dose of several trillion nanorobots), then exit the cell and tissue, re-enter the bloodstream, and finally eliminate themselves from the body through the kidneys. DECHRONIFICATION: A TREATMENT FOR THE DISEASE OF NATURAL DEATH The end result of all these nanomedical advances will be to enable a process I call ‘dechronification’ – or, more colloquially, ‘rolling back the clock’. I see no serious ethical problems with this. According to the volitional normative model of disease that is most appropriate for nanomedicine [19], if you’re physi- ologically old and don’t want to be, then for you, oldness and aging –and natural death – are a disease and you deserve to be cured. Dechronification will first arrest biological aging, then reduce your biological age by performing three kinds of proce- dures on each one of the 4 trillion tissue cells in your body: First, a respirocyte – or microbivore – device will be sent to enter every tissue, to remove accumulating metabolic toxins and undegradable material. Afterwards, these toxins will con- tinue to slowly re-accumulate as they have all your life, so you’ll probably need a whole-body cleanout to prevent fur- ther aging, maybe once a year. Second, chromosome replacement therapy can be used to correct accumulated genetic damage and mutations in every one of your cells. This might also be repeated annually, or less often. Third,  persistent  cellular  structural  damage  that  the  cell cannot repair by itself such as enlarged or disabled mitochon- dria can be reversed as required, on a cell-by-cell basis, using cellular  repair  devices.  We’re  still  a  long  way  from  having complete theoretical designs for many of these machines, but