Calcium helps in muscle contractions. Nerve conduction & clotting ++ Vitamin D – Increases Ca PTH – Increases Ca++ & Decreases PO4SKIN 7 Hydroxy Cholestrol Cholecalciferol Vit D3 25 Hydroxy Vit D3 By Liver Enzymes 25 Hydroxylase LIVER Phosphate helps in biochemical process and energy Calcitriol – Increases Ca++ Calcitonin – Decreases Ca++ PARATHYROID GLANDS PTH PTH Ca++ PTH + + + 1 α Hydroxylase 25 Hydroxy Vit D3 CALCIDIOL + Ca++ PO4- 1, 25, Dihydroxy D3 CALCITRIOL INCREASE Ca++ in Nephrom PTH Receptor KIDNEY BONE GUT Ca++ PTH increases activity of PO4- 1 α Hydroxylase Absorption