1. Heart valves. We haven't got a replacement for your heart yet — though a lot of people are researching it — but you can replace your heart valves with artificial ones like those manufactured by ATS Medical. These simple-looking device are fitted to your heart, opening and closing with each beat of your heart to push the blood through your body. Without heart valves, your heart has to work much harder to pump and will grow enlarged — generally a condition that leads to death. Many people are born without a heart valve, or lose one in a heart attack. They can also be replaced by heart valves from a dead human or pig.

2. Bladder. Tissue engineers have successfully grown bladders from human bladder cells, then transplanted them back into the patients whose malformed or damaged bladders provided the cell samples. Several people have received these synthetic biological bladders since 2006. They are beta bladders, and the patients aren't always continent. But now they have full-sized bladders when they didn't before, and that dramatically improves quality of life. So you can survive if you lose your bladder — just as long as you've got a few bladder cells left for tissue engineers to grow you a new one.

3. Large intestine. Many people with colitis — an immuno-deficiency disease that causes inflammation and tearing of the colon — have colectomies to remove the entire organ. But that doesn't mean they have to wear a colostomy bag. Surgeons can use a section of the small intestine to create a J-shaped pouch inside your body that acts as a surrogate colon. It's not as big as your large intestine was, so you have to visit the bathroom a bit more often. But you don't have to wear a bag, and you're surviving just fine with no colon at all.

4. Stomach. Like your large intestine, your stomach can be completely removed. Usually this is done when you have stomach cancer. The esophagus (the pipe that routes food from your mouth to your stomach) is rerouted to connect to your small intestine, and the surgeon can widen the small intestine in that area to create a surrogate stomach. Food goes through the same digestive process as before, but you can't absorb as much vitamin B12. So you may have to get bi-annual injections of the vitamin. 5. Kidneys. You've probably heard about kidney dialysis, where people with kidneys that don't function get stuck in a giant machine that de-toxifies their blood for hours. It's a crappy process, but it does mean that you can live without a kidney. The good news, though, is that there is now a wearable dialysis device, pictured above, which you put on your body like a belt. It doesn't work quite as well as dialysis, but it does the trick and many patients prefer it to the weekly dialysis clinic visit. We've written about the kidney dialysis wearable, and heart valves, before.

Top image "The Food" from artist Jeanne Dunning.

With this small, wearable device (see photo and diagram), people who suffer from kidney problems might never have to get dialysis again. The machine would do the dialysis for them. Kidneys purify our blood, among other things, and so this device would do that job, sucking your blood out, passing it through a purifying filter, and then pumping it back into your body after removing toxic waste and passing that out to an external bag. The device from Xcorporeal is a bit bulky and awkward, but patients say it beats getting hooked up to a dialysis machine for 12 hours a week. Photo via Lancet.

Artificial heart valve and Wearable Artificial Kidney [MedGadget]