GENERAL HISTOLOGY

Detailed explanation-1: -Parathyroid hormone (PTH) is a hormone that your parathyroid glands make and release to control the level of calcium in your blood by increasing it. PTH also helps control the levels of phosphorus (a mineral) and vitamin D (a hormone) in your blood and bones.

Detailed explanation-2: -Parathyroid hormone or PTH PTH acts on the kidney to conserve calcium and to stimulate calcitriol production, which increases intestinal absorption of calcium. PTH also acts on the bone to increase movement of calcium from bone to blood.

Detailed explanation-3: -Calcitonin is involved in helping to regulate levels of calcium and phosphate in the blood, opposing the action of parathyroid hormone. This means that it acts to reduce calcium levels in the blood.

Detailed explanation-4: -Parathyroid hormone is directly involved in the bones, kidneys, and small intestine. In the bones, PTH stimulates the release of calcium in an indirect process through osteoclasts which ultimately leads to the resorption of the bones.