Final answer:
Parathyroid hormone and calcitonin are the hormones that regulate the level of calcium in the blood.
Step-by-step explanation:
The level of calcium in the blood is regulated by two hormones: parathyroid hormone (PTH) and calcitonin. When blood calcium levels drop, the parathyroid glands release PTH, which stimulates the release of calcium from bone and increases calcium reabsorption by the kidneys. PTH also activates vitamin D in the kidney, which enhances the absorption of dietary calcium by the intestines. On the other hand, calcitonin helps to lower blood calcium levels by inhibiting bone resorption.