Question

Parathormone is secreted when there is

• A. Increased Ca${}^{2+}$ level in blood
• B. Decreased blood Ca${}^{2+}$ level
• C. Increased blood sugar level
• D. Decreased blood sugar level

Answer 1

The correct option is B Decreased blood Ca${}^{2+}$ level

The parathyroid glands secrete a peptide hormone called parathyroid hormone or parathormone (PTH). The release of parathromone is regulated by the circulating levels of calcium ($C{a}^{2+}$) ions in the blood. PTH plays an important role in calcium balance of the body. It maintains the calcium balance between the blood and other tissues. When the calcium level in the blood decreases, parathyroid hormone is released in order to increase the calcium level in the blood. PTH acts on bones and other skeletal structure and mobilizes the calcium ($C{a}^{2+}$) from the bones into the blood. This is called bone resorption/dissolution/demineralization. The parathromone also increases the reabsorption of calcium by the renal tubules and absorption of calcium from the digested food. Hence, PTH (parathormone) is a hypercalcemic hormone that increases the blood calcium levels.