Question

The blood calcium level is lowered by the deficiency of-
A. Both calcitonin and parathormone
B. Calcitonin
C. Parathormone
D. Thyroxine

Answer 1

Hint: The calcium level in our body is balanced by an exchange between the blood and the bone. In the case of low blood calcium level, the body compensates it by resorbing the bone tissues.

Complete answer:
The blood calcium level in a healthy individual ranges from 8.6 to 10.3 mg/dL. In order to maintain a healthy calcium level in the body, it uses hormones such as the Parathyroid hormone and Calcitonin to regulate blood calcium levels. The blood calcium level is lowered by calcitonin and increased by the parathyroid hormone.
Parathyroid hormone is secreted from parathyroid glands which are four in number and are located behind the thyroid gland in the neck. Parathyroid hormone regulates the level of calcium in the blood by increasing the levels when they become low. Calcitonin or Thyrocalcitonin is released by the thyroid gland. It is involved in the regulation of levels of calcium and phosphate in the blood, opposing the action of parathyroid hormone, i.e. it reduces calcium levels in the blood.

Additional Information:
Major functions of calcium in the human body are-
- Calcium is very essential in muscle contraction.
- It is necessary for oocyte activation, blood clotting, and nerve impulse transmission.
- It provides strength to bones and teeth.
- It helps in regulating heartbeat and fluid balance within cells.
- It acts as a secondary messenger for the transport of molecules across the cell.

So, the correct answer is ‘Parathormone'.

Note: The absorption of calcium from the intestine takes place with the help of Vitamin D. Calcitriol, the active form of Vitamin D3, absorbs calcium from the intestine of human beings. Blood calcium levels can also be increased by increasing the reabsorption of calcium from the kidney. All these help in the elevation of decreased blood calcium levels.