Osteocytes are mature bone cells, osteoblasts are cells allowing new bone formation, and osteoclasts are cells that remodel bone by breaking down bone calcium. Osteocytes come from osteoblasts inside the bone. Osteoclasts originate from bone marrow, but resume on the surface of bone minerals beside the bone being dissolved. When calcium becomes low Parathromone increases blood calcium levels and decreases phosphate levels, making sure calcium is always available, but if calcium is high PTH is inhibited. Parathormone is released by blood calcium levels and vitamin D Three hormones regulating calcium levels include: parathormone, calcitonin, and 1, 25-dihydroxyvitamin D3. PTH forms pre-pro- parathormone (115 amino acids long), cleaving to form…show more content… Vitamin D starts with 7-dehydrocholesterol,made in the liver, comes in contact with sunlight forming Previtamin D3, producing cholecalciferol. Vitamin D3 travels to the blood stream to be metabolized in the liver by 25-Hydroxylase. Next, the inhibited 1-Hydroxylase enzyme, in the kidney’s, becomes activated by Parathormone forming 1, 25dihydroxycholecalciferol vitamin D3. Vitamin D3 allows for kidney calcium reabsorption, removes calcium through osteoclast, activates the absorption of calcium from intestines, and eliminates phosphate from the kidneys through parathormone stimulating 1-Hydroxylase, and when finished vitamin D3 is inactivated by 24-Hydroxylase. If the parathormone gland is removed the hypocalcemic stimulation of vitamin D disappears, proving the 1-Hydroxylase activity is induced by parathormone, making parathormone necessary for vitamin D production. With the presence of phosphate is the presence of calcium, if kidneys can’t remove the phosphate, 1-Hydroxylase is inhibited, and no vitamin D is produced. Pepsi contains phosphate, and when you need calcium, this phosphate drink increases phosphate levels, causing 1-Hydroxylase inhibition by PTH, Your body assumes if there’ s excess phosphate there’s excess calcium. Therefore 1-Hydroxylase is inhibited preventing vitamin D3 formation, the calcium available is excreted from kidney’s, causing bone