Question

Thyrocalcitonin
A) Elevated $K^+$ level in blood
B) Lowers $Ca^{2+}$ level in blood
C) Elevates $Ca^{2+}$ level in blood
D) None of the above

Answer 1

Hint: Thyrocalcitonin, also referred to as calcitonin, is a polypeptide hormone secreted by the thyroid gland's parafollicular or C cells. It decreases the levels of calcium and phosphate in the blood and stimulates the growth of bones.

Complete answer:
As the amount of blood calcium increases above the normal level, a polypeptide enzyme made up of 32 amino acids called thyrocalcitonin is released by the parafollicular cells of the thyroid gland to bring the level of blood calcium into the normal range.

By increasing the absorption of calcium into the bone and reducing the absorption of calcium into the kidneys and intestines, thyrocalcitonin reduces the number of calcium ions in the blood. The effect of parathyroid hormone is neutralized by thyrocalcitonin, thereby lowering blood calcium levels in the blood.

Additional information:
In addition, the thyroid gland also secretes a protein hormone named thyrocalcitonin, or tetraiodothyronine or thyroxine (T4) and triiodothyronine (T3). Thyrocalcitonin reduces the amount of blood calcium (TCT). It counters the action of the hormone parathyroid, which raises the calcium level in the blood. 24 hours a day the parathyroid glands regulate the calcium in the blood.

In reaction to the amount of calcium in the blood, the four parathyroid glands release more or less Parathyroid Hormone (PTH). The parathyroid glands release more PTH to raise blood calcium levels when the calcium in our blood goes too low.

Thus, the correct answer is option ‘C’.

Note: Whatever its cause, calcitonin causes a decrease in sodium, phosphate and calcium renal tubular reabsorption. Calcitonin is secreted by glandular ultimobranchial body cells in birds, fish, and other non-mammalian vertebrates.