Question

How do hormones from the thyroid and parathyroid regulate the calcium concentration of the blood?

• A. Calcitonin raises the blood calcium and parathormone lowers the blood calcium level.
• B. Calcitonin lowers the blood calcium and parathormone raises the blood calcium level.
• C. Both parathormone and calcitonin reduce the calcium level in the blood.
• D. Both parathyroid and calcitonin raise the calcium level in the blood.

Answer 1

The correct option is B

Calcitonin lowers the blood calcium and parathormone raises the blood calcium level.

Calcitonin helps in lowering the level of calcium in blood by depositing excess calcium in bones and by preventing the mixing of calcium from the bones with blood. Calcitonin also helps in the excretion of the excess of calcium through the kidneys in the urine. However, the parathormone, secreted by the parathyroid glands, is responsible for increasing blood calcium levels by absorbing calcium to the blood from the kidneys. Both calcitonin and the parathyroid gland are antagonistic (opposite) to each other.