Parafollicular cells, which are also known as the C-cells, of our thyroid gland. Thyrocalcitonin hormone helps in regulating the calcium and phosphate levels in the blood. It acts to reduce the level of calcium in the blood. It obstructs the osteoclasts activities which are responsible for the breaking down of the bones. It also reduced the absorption of calcium in our kidneys in order to lower the calcium level in our blood.