Thus, the feces contain unabsorbed dietary calcium and unreabsorbed digestive juice calcium.
The metabolism of calcium and phosphorus is closely related and influenced by parathyroid hormone (PTH), vitamin D, and, to a lesser extent, calcitonin. Bone remodeling of calcium and phosphorus integrates for four systems. The gastrointestinal system of endocrine system marked by parathyroid hormone (PTH) and vitamin D the renal system where vitamin D is activated and where calcium and phosphorus are both filtered and reabsorbed. The musculoskeletal system with bone resorption and formation of PTH where it will sensing receptors in the PTH and changes in ionized calcium and subsequently vary its release of PTH which acts to increase the plasma calcium. The decreases of calcium will stimulate the production and release of PTH whereas increases in calcium will suppress production and release of PTH. The calcium will enters the body is via oral intake followed by the absorption but some of this lost in the feces bones are in a constant balance between formation and resort that is called bone turnover.