Not many folks know what the parathyroid is or does until -- as with pretty much everything within our bodies -- something goes wrong. Parathyroid hormones regulate calcium in the blood, which affects bone growth among other things. Folks with elevated amounts of the hormone have trouble with, according to Popular Science magazine, "stones (kidney stones), bones (fractures), moans (psychiatric problems) and groans (constipation)." A surprising new way to deal with parathyroid imbalance involves autotransplantation -- instead of getting someone else's parathyroid (rejection is always a problem), they take yours out, then put it back. Sometimes they even put it back in your arm rather than in your neck, where it belongs. Isn't that amazing?