Endocrine system calcitonin

Calcium is present in three forms e.g., as free calcium ion, bound to plasma protein albumin and in diffusable complexes. The endocrine system, through parathyroid hormone and calcitonin, helps in keeping the concentration of ionized plasma calcium in normal level. Decrease in plasma levels of ionized calcium leads to increased parathyroid hormone secretion. Parathyroid hormone tends to increase plasma calcium level by increasing bone resorption, increasing intestinal absorption and increasing reabsorption of calcium in kidney. Vitamin D acts by stimulating... 

Limited data are available on in vitro effects of barium on the endocrine system. Studies done with isolated pancreatic islet cells from mice show barium is transported across the cell membrane and incorporated into organelles, especially the mitochondria and secretory granules (Berggren et al. 1983). Barium was found to increase cytoplasmic calcium consequently, the insulin- releasing action of barium may be mediated by calcium. Barium has also been found capable of stimulating the calcitonin secretion system of the thyroid in pigs (Pento 1979). 

Because of the high calcium content of sea water, aquatic animals have no problems in accruing calcium from the environment in sufficient amounts. In fact, during evolution they have developed the calcitonin endocrine system, that shields their organisms from being flooded with calcium. The... 

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