Final answer:
Calcitonin and Parathormone are hormones that help maintain blood calcium levels. Calcitonin decreases blood calcium by inhibiting bone breakdown and promoting calcium deposition in bones, while PTH increases calcium levels by stimulating bone breakdown and augmenting calcium absorption and reabsorption.
Step-by-step explanation:
The role of Calcitonin and Parathormone (PTH) is to regulate calcium levels in the blood, maintaining calcium homeostasis. Calcitonin, produced by the parafollicular cells of the thyroid, is released when blood calcium levels are high and functions to decrease these levels. It does so by inhibiting osteoclasts (which break down bone), promoting the activity of osteoblasts (which build bone), and enhancing calcium excretion by the kidneys. As a result, calcium is deposited in the bones, strengthening bone structure. Conversely, PTH, released by the parathyroid glands, increases blood calcium concentrations when they dip too low, by enhancing kidney reabsorption of calcium, stimulating osteoclast activity, inhibiting osteoblasts, and enhancing absorption of calcium by the digestive system through the synthesis and release of calcitriol.
While the role of calcitonin is somewhat unclear in healthy nonpregnant, unstarved adults, it becomes significant in other situations such as in children, during pregnancy, and during prolonged starvation to protect bone integrity. PTH and calcitonin are essential in maintaining bone health, and pharmaceuticals of calcitonin are sometimes used to treat conditions like osteoporosis and osteoarthritis.