PATHOLOGY

Detailed explanation-1: -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-2: -Parathyroid hormone (PTH) paradoxically causes net bone loss (resorption) when administered in a continuous fashion, and net bone formation (deposition) when administered intermittently.

Detailed explanation-3: -Calcitonin increases Wnt10b and bone formation but decreases bone resorption in ovariectomized osteoporotic rats.

Detailed explanation-4: -Calcitonin was discovered as a peptide hormone that was known to reduce the calcium levels in the systemic circulation. This hypocalcemic effect is produced due to multiple reasons such as inhibition of bone resorption or suppression of calcium release from the bone.