Looking toward a future of total bodily replacement with machines, website Io9 has a roundup of organs that can be replaced with synthetic versions, including kidneys via dialysis and the J-pouch, which acts as a "surrogate colon." The article, entitled "How Many of Your Internal Organs Can You Live Without?", doesn't go into the gallbladder and spleen, the two organs you actually can live without, or the thyroid, which can be replaced with meds. {artificial heart illustration by Mike Altman}