question_answer 44)

  Calcium ion concentration in blood affects muscle contraction. Does it lead to tetany in certain cases? How will you correlate fluctuation in blood calcium with tetany?

Answer:

                For the muscle fibre to contract, the binding site on thin filaments must be uncovered. This occurs when  bind to another set of regulatory proteins, called troponin complex which control the position of tropomyosin on the thin filament. The calcium binding rearranges the tropomyosin, troponin complex, exposing the myosin-binding sites on the thin filament. When is present in the cytosol, the thin and thick filament slide part each other resulting in muscle contraction. Similarly, when the concentration falls, the binding sites get covered and contraction stops. In case of tetany there occur low calcium levels in body fluid due to diminished function of parathyroid gland. This gland is mainly involved in the secretion of parathyroid hormone which is associated in regulating calcium levels in blood. Tetany results in periodic painful muscular spasm (wild contraction) and tremors.