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8 Cards in this Set

  • Front
  • Back
Describe the dietary factors that influence bone.
• 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
Describe the roles of calcitonin and parathyroid hormone in the regulation of blood calcium.
• 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
Describe the vitamin D pathway, and the role of calcitriol in calcium homeostasis.
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
Describe the role of dietary calcium in maintenance of bone mass and know the recommended allowance for calcium intake for young adults.
• 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)
Describe how exercise can affect bone mass.
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
Describe the role of growth hormone, thyroxine and sex hormones in modulating bone mass.
Describe the skeletal disorders that arise from abnormal levels of human growthhormone.
Define osteoporosis and identify the risk factors for development of the disease. Offer strategies for prevention of osteoporosis.