NTS 135 Lecture Notes - Malabsorption, Cholecalciferol, Calcitriol
Document Summary
Can vitamin d be toxic: vitamin d. Produced in the skin when exposed to uv light. Activation occurs in liver and kidneys: forms of vitamin d. Vitamin d2 (ergocalciferol: synthetic product derived from irradiation of plant sterols (ergosterol, used in some supplements. 7-dehydrocholesterol: precursor of vitamin d found in skin. Vitamin d3: previtamin form synthesized in skin found naturally in some animal sources, including fish and egg yolks, synthesis of vitamin d. 7-dehydrocholesterol: precursor found in skin, converted to vitamin d3 by sunlight exposure. Vitamins d2 and d3 travel to liver, converted to 25-hydroxyvitamin d3 (calcidiol: main form of vitamin d found in blood. Calcidiol: chemically converted in kidneys to 1, 25-dihydroxyvitamin d3 (calcitriol, biologically active form of vitamin d, vitamin d and sun exposure. Binds to and affects cells of: immune system: brain and nervous system, parathyroid gland, pancreas, skin, muscles reproductive organs. Regulator of cell growth: skin, colon, prostate, breast.
