Tetany is an involuntary and forcibly contracted muscle that does not relax and occurs when the concentration of calcium ions (Ca++) is low in bone only.The muscles become hypersensitive to any remaining calcium. Calcium ion conc is present in sarcoplasm reticulum causes contractions and the nervous system becomes increasingly excitable, and nerves discharge spontaneously, sending impulses to skeletal muscles and causing spasmodic contractions.firing rate of the motor neurons is increased. So i guess low calcium in bone (reservior for calcium) leads to hypoparathyroidism and muscle depends on calcium present only in sarcoplasm .get exicited and causes tetany ...i think so...
Hypoparathyroidism is the state of decreased secretion or decreased activity of parathyroid hormone (PTH). This lack of PTH leads to decreased blood levels of calcium (hypocalcemia) and increased levels of blood phosphorus (hyperphosphatemia). The symptoms of hypoparathyroidism result from the low levels of calcium in the blood, not a lack of PTH and can range from quite mild (tingling in the hands, fingers, and around the mouth) to more severe forms of muscle cramps leading all the way to tetany (severe muscle cramping of the entire body).
Muscle contractions occurs as long as ATP is available and calcium is present on thin filament.The calcium ions leave the troponin molecule in order to maintain the calcium ion concentration in the sarcoplasm. The active pumping of calcium ions into the sarcoplasmic reticulum creates a deficiency in the fluid around the myofibrils. This causes the removal of calcium ions from the troponin. Thus the tropomyosin-troponin complex again covers the binding sites on the actin fiaments and contraction ceases.
