Answer:
Three major hormones (PTH, vitamin D, and calcitonin) interact to maintain a constant concentration of calcium, despite variations in intake and excretion.
Step-by-step explanation:
The second major hormone involved in the regulation of calcium metabolism and skeletal remodeling is vitamin D, which includes cholecalciferol (vitamin D3) of animal origin, as well as ergocalciferol (vitamin D2) of plant origin.