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8 Cards in this Set
- Front
- Back
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Describe the dietary factors that influence bone.
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• Minerals:
• calcium and phosphorus (also magnesium, fluoride and manganese) • Vitamins: • Vitamin A → stimulates activity of osteoblasts • Vitamin C →needed for collagen synthesis • Vitamin D → stimulates calcium absorption • Vitamins K, B12 → needed for synthesis of bone proteins |
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Describe the roles of calcitonin and parathyroid hormone in the regulation of blood calcium.
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• Calcitonin- hormone involved in calcium homeostasis
• Stimulus: high blood calcium • Source: thyroid gland (parafollicular cells) • Target tissue: bone, kidney, intestine • Actions (goal is to decrease blood Ca): • Inhibits osteoclast activity (decreased bone resorption) • Increases excretion of calcium at kidney • Inhibits absorption of calcium at intestine End result: decrease blood calcium • Parathyroid Hormone- hormone involved in calcium homeostasis • Stimulus: low blood calcium • Source: parathyroid gland • Target tissues: bone, kidney, intestine • Actions (goal is to increase calcium): • Stimulates osteoclast activity (increased bone resorption) • Decreases excretion of calcium at kidney • Stimulates intestinal absorption of calcium and promotes calcitriol (Vit. D) action End result: increase blood calcium |
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Describe the vitamin D pathway, and the role of calcitriol in calcium homeostasis.
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Vitamin D Pathway:
• Calcitriol: active form of vitamin D • 1, 25 dihydroxycholecalciferol or • 1, 25 dihydroxy vitamin D3 • Vitamin D is a steroid hormone – derived from cholesterol (lipophillic / hydrophobic) • Stimulates osteoclast activity (increases bone resorption) • Decreases calcium excretion at the kidney • Increases calcium absorption at the intestine (works well with PTH to stimulate absorption) End result: increase blood calcium |
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Describe the role of dietary calcium in maintenance of bone mass and know the recommended allowance for calcium intake for young adults.
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• How much calcium should you have per day?
• Young adults (19-50 years old) need 1000mg calcium from diet and supplements to avoid bone loss • Maintaining calcium in blood is priority • 8.5-11.0→ this is maintained even when we have too much or too little (unless tumor affects this) |
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Describe how exercise can affect bone mass.
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Role of exercise
Goal: reach the fracture threshold later in life • Exercise early in life – increase peak bone mass • Exercise later in life – prevent bone loss Other benefits of exercise – fall prevention – Improved strength – Improved balance and coordination |
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Describe the role of growth hormone, thyroxine and sex hormones in modulating bone mass.
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Describe the skeletal disorders that arise from abnormal levels of human growthhormone.
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Define osteoporosis and identify the risk factors for development of the disease. Offer strategies for prevention of osteoporosis.
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