MICROANATOMY

Detailed explanation-1: -How is parathyroid hormone controlled? Parathyroid hormone is mainly controlled by the negative feedback of calcium levels in the blood to the parathyroid glands. Low calcium levels in the blood stimulate parathyroid hormone secretion, whereas high calcium levels in the blood prevent the release of parathyroid hormone.

Detailed explanation-2: -Parathyroid hormone decreases phosphate reabsorption at the proximal convoluted tubule. Phosphate ions in the serum form salts with calcium that are insoluble, resulting in decreased plasma calcium. The reduction of phosphate ions, therefore, results in more ionized calcium in the blood.

Detailed explanation-3: -Answer and Explanation: The correct answer is (B) plasma calcium concentration. Parathyroid hormone is secreted by the thyroid glands. The main function of this hormone is to regulate the level of calcium in the blood.

Detailed explanation-4: -Blood calcium levels are regulated by parathyroid hormone (PTH), which is produced by the parathyroid glands.

Detailed explanation-5: -Calcium levels are regulated by the parathyroid glands. That’s all the parathyroid glands do! Through the secretion of parathyroid hormone (PTH), these four small glands regulate how much calcium is absorbed from our diet, how much calcium is secreted by our kidneys, and how much calcium is stored in our bones.