Calcitonin is regulated by which gland to ensure calcium sufficiency?

Calcitonin is a hormone primarily involved in the regulation of calcium levels in the body, and it is produced by the parafollicular cells (C cells) of the thyroid gland. The primary function of calcitonin is to lower blood calcium levels when they are too high. It does this by inhibiting osteoclast activity in the bones (which breaks down bone and releases calcium into the bloodstream), decreasing renal tubular reabsorption of calcium, and therefore promoting its excretion in urine.

Since the question specifically asks for the gland that regulates calcitonin to ensure calcium sufficiency, the thyroid gland is the correct answer because it is responsible for the production of calcitonin in response to elevated calcium levels in the blood. The parathyroid gland, on the other hand, produces parathyroid hormone (PTH), which works in opposition to calcitonin by increasing blood calcium levels when they are too low.

Therefore, recognizing that calcitonin is regulated and secreted by the thyroid gland is essential for understanding how the body maintains calcium homeostasis.