calcitonin: thyroid hormone that tends to lower the level of calcium in the blood plasma and inhibit resorption of bone
hormone: the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect
periosteum: a dense fibrous membrane covering the surface of bones (except at their extremities) and serving as an attachment for tendons and muscles; contains nerves and blood vessels that nourish the enclosed bone