Which of the following statements is true related to hormones that regulate blood calcium levels?
1. Calcitonin causes bone to be broken down. 2. Calcitonin is released by the parathyroid gland to help lower blood calcium levels. 3. Parathyroid hormone is released by the parathyroid gland to help lower blood calcium levels. 4. Calcitonin is released by the thyroid gland to help lower blood calcium levels.
