Question

Parafollicular cells of thyroid secrete hormone for controlling level of
A. K+
B. Na+
C. Ca+
D. Mg+

Answer 1

1. Parafollicular cells are neuroendocrine cells inside thyroid gland.
2. They secrete the hormone calcitonin.

Complete answer:
Option A: The K+ ion levels in the body are maintained through renal filtration. A hormone named aldosterone is responsible for controlling potassium levels. Aldosterone is secreted by the adrenal glands. Therefore, this is the incorrect option.

Option B: The body maintains sodium homeostasis by its excretion through urine. Aldosterone secreted by the adrenal gland is the hormone responsible for the regulation of sodium ion levels in the blood. Therefore, this is the incorrect option.

Option C: The calcium regulation is done with the help of specific hormones, named parathyroid hormone, calcitriol, and calcitonin. Calcitonin is secreted by parafollicular cells of the thyroid gland. Therefore this is the correct answer.
Calcium is the most abundant mineral in the human body. Their levels in blood plasma are narrow and regulated strictly with the help of the above-mentioned hormones. Calcitonin is released when calcium levels are high in plasma. The reservoir of calcium is bone. Calcium is deposited in bones and is withdrawn from the bone when necessary through bone remodeling. Calcitonin inhibits the resorption of bone.

Option D: Magnesium levels in the body are regulated constantly by intestinal uptake and renal excretion. Parathyroid hormones are responsible for the regulation of magnesium levels. They are secreted by parathyroid glands. Therefore, this is the incorrect option.

Hence, the correct answer is option (C)

Note: Parafollicular cells also secrete neuroendocrine molecules such as serotonin, somatostatin, and CGRP. They also regulate local thyroid hormone production.
Calcitonin has opposite effects of parathyroid hormone.