The |parathyroid| |glands| are small |glands|, usually four in number, embedded within the back of the |thyroid|. These |glands| produce the ~hormone~ parathormone, which regulates the level of calcium and phosphorus in the ~blood~ and bones. Parathormone tends to increase the concentration of calcium in the ~blood~ by increasing bone breakdown. This ~hormone~ has the opposite effect of calcitonin (thyrocalcitonin) which is secreted by the |thyroid| gland. Calcium plays an important role in many metabolic processes; too much calcium (hypercalcemia) or too little calcium (tetany) can disrupt the normal function of the muscles and ~nerves~. Parathormone functions to help maintain homeostasis of ~blood~ calcium. The body's cells are extremely sensitive to changing amounts of ~blood~ calcium.
