Question

Calcitonin is a thyroid hormone, which
(a) Elevates potassium level on blood
(b) Lowers calcium level in the blood
(c) Elevates calcium level in the blood
(d) Has no effect on calcium

Answer 1

Hint: A protein hormone that is secreted by the thyroid gland in the form of C cells. They are responsible for the regulation of calcium and potassium levels in the blood and act opposite to the parathyroid gland.

Complete answer:
Calcitonin is a peptide hormone made up of a chain of the protein molecules that reduces the blood calcium level. In humans, it is secreted by the thyroid gland that belongs to the group of the pituitary glands while in animals it is produced in the neck region called ultimo pharyngeal body.
- The primary role of the calcitonin hormone is to reduce the level of calcium in the blood.
 - It counteracts the role of parathyroid glands.
- In humans, this hormone is not of much importance, and its real function is still not known properly.
- In the case of fish, birds, reptiles, and other mammals the presence of calcitonin is known and established.
- The inactive proteins also called proprotein when undergo breakage will give rise to calcitonin.
- The more the gastrin, pentagastrin, and serum are released the more calcitonin being produced.
 - Calcitonin functions through two major pathways:
(a) By inhibiting the repair and damage activity of the bone cell leading to osteoclast that results in the breakage of bones and lowers the level of calcium.
(b) It stops the activity of the absorption of calcium and potassium in the renal tubules of the nephrons and this leads to the excretion of these ions in the urine, thus lowering their level in the blood.
So, the correct answer is ‘Lowers calcium level in the blood’.

Note: The calcitonin was earlier thought to be produv]ced by the parathyroid glands but the team of researchers under the scientist Iain Macintyre showed that the hormone is released by the thyroid gland in the Royal Postgraduate School of London. In 1962 the hormone calcitonin was first produced at the University of British Columbia in Canada by Douglas Harold Copp and B. Cheney. The name calcitonin was first discovered by DR. Copp.