PHAR 441 Lecture Notes - Lecture 4: Ergosterol, Duodenum, Polydipsia
14 Sep 2016
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Otc supplements: vitamin d2 or d3 made by uv radiation of ergosterol (d2) and 7-dehydrocholesterol (d3) Vitamin d3: skin: uv rays convert provitamin d3 (7-dehydrocholesterol) to vitamin d3 (cholecalciferol, liver: 25-hydroxylase converts cholecalciferol to calcifediol (25-oh-d3, kidney: 1- -hydroxylase converts calcifediol to calcitriol (1,25-oh2 vitamin d3) Same enzymes, but it goes: provitamin d2 (ergosterol) vitamin d2 (ergocalciferol) vitamin d2 (25- Increases plasma [ca2+] and [pi] works with calcitonin and pth. Maintains homeostasis of [ca2+] and [pi] within a narrow physiological range. Hypertension downregulates production of renin (too much renin causes high blood pressure) proliferation and induction of their differentiation and promotes epidermal differentiation. Increases ca2+ and pi absorption by the small intestine (duodenum and some jejunum) 10% to 30-40% of ca2+ in the small intestine. Ca2+ and pi from the bone (if dietary ca2+ is insufficient) Increases ca2+ and pi re- absorption by the kidney. Decreases ca2+ and pi excretion by the kidney.
