BIOM 3200 Final: Unit 02 Questions

• School: University of Guelph
• Department: Biomedical Sciences
• Course: BIOM 3200
• Professor: Nicole Campbell

Document Summary

2. 01 identify three hormones that mediate calcium homeostasis. Calcitonin (thyroid gland), parathyroid hormone (parathyroid gland) and 1,25-dihydroxycholecalciferol (kidneys) are three hormones involved in the regulation of calcium and phosphate metabolism. 2. 02 describe the effects of vitamin d on calcium absorption and indicate the cellular mechanism. Calcium poorly absorbed in intestinal tract compared to phosphate (except when excess calcium present): vit. D has an effect on the absorption from the gastrointestinal tract and on both bone deposition and bone reabsorption. In small quantities, vitamin d (through 1,25-dihydroxycholecalciferol) promotes bone calcification. increasing both calcium and phosphate absorption from the intestines, but even without increased absorption, there is increased mineralization of bone. 2. 03 identify and describe the steps in the formation of active vitamin d3 (1, 25- dihydroxycholecaliferol) D must first be converted to 1,25-dihydroxycholecalciferol in the kidney: parathyroid hormone is used for formation of 1,25-dihydroxycholecalciferol. If plasma concentration is high, formation of 1,25-dihydrocholecalciferol is depressed which reduces calcium absorption.