Question

Which of the following in mammals does not play a central role in calcium balance in the human body?

• A. Thymosin
• B. Vitamin D
• C. Parathyroid hormone
• D. Thyrocalcitonin

Answer 1

The correct option is A Thymosin

Vitamin D:

Vitamin D helps in the absorption of $C{a}^{2+}$ from the intestine and maintains the normal level of $C{a}^{2+}$ ions in the blood. This assists in bone formation.



Parathyroid hormone:

Parathyroid hormone released from the parathyroid glands plays a role in maintenance of calcium-phosphorus balance in the blood. It increases the calcium ions in the blood in the following ways:-

• Bone demineralisation: Stimulating the release of calcium from bones
• Reabsorption of calcium ions from the renal tubules
• Absorption of calcium ions from the digested food

Thyrocalcitonin:

Thyrocalcitonin is released from the parafollicular cells of the thyroid gland. It lowers the level of blood $C{a}^{2+}$ by the following ways:-

• Inhibiting the release of $C{a}^{2+}$ from the bones by limiting the activities of osteoclasts
• Limiting the absorption of calcium from the digested food after a certain level
• Increased excretion of calcium ions via urine

Thymosin :

Thymosin is released from the thymus glands and plays a role in the differentiation of the T cells and stimulating antibody production from the B cell, thus promoting immunity


Final answer: d. Thymosin