Secrete a hormone that controls the blood calcium level

The parathyroid glands secretes PTH hormone that controls the blood calcium level.

Explanation:

The PTH is the parathyroid hormone which is secreted by parathyroid gland. It maintains the blood calcium level whenever required in the body.

The hormone increases the amount of calcium by preventing calcium excretion from the urine. The PTH also stimulates the release of calcitriol. The calcitriol allows absorption of calcium from the diet.