2011 Calcium Metabolsim and Control of Growth

2011 Calcium Metabolsim and Control of Growth - Dr Kennon M...

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E-76 Dr. Kennon M. Garrett CALCIUM HOMEOSTASIS AND CONTROL OF GROWTH Reading: Vander et al., Human Physiology, 12 th ed. pp. 340-349. Behavioral Objectives 1. List the functions of osteoclasts and osteoblasts in bone resorption and bone formation 2. List the hormones responsible for Ca regulation. 3. Describe the synthesis of 1,25-dihydroxy vitamin D3 4. Describe the mechanisms by which parathyroid hormone regulates Ca homeostasis. 5. List factors that affects growth. 6. List effects and mechanisms of growth hormone on growth. 7. Describe the regulation of growth hormone release. 8. List effects of IGF-1 on growth. 9. List other hormones that affect growth and know what effects they have on growth. I. Calcium Regulation A. Organs involved in Ca 2+ regulation 1. GI tract Ca 2+ is absorbed from the small intestine. Approximately 1 gm of Ca 2+ is ingested each day and the GI tract absorbs about 1/3 of the ingested Ca 2+ . The absorption of Ca 2+ is regulated by 1,25- dihydroxyvitamin D 3 . 2. Kidneys The kidneys reabsorb 99% of the filtered Ca 2+ . 90% is reabsorbed in the proximal tubule and loop of Henle. 9% is reabsorbed in the distal segment and is regulated by parathyroid hormone. The kidneys play an indirect role in Ca 2+ regulation though the synthesis of 1,25- dihydroxyvitamin D 3 3. Bone - the major storage site for Ca 2+ and phosphate
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