Exam 3 Review Guide - Bone Health Strength, flexibility 65%...

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Bone Health Strength, flexibility 65% minerals for hardness; 35% organics for strength, durability, flexibility Collagen: fibrous protein in bone tissue Trabecular bone ≈ spongy – found at ends of bone Cortical bone ≈ compact –found in body of bone Growth (womb adulthood): Determines size Modeling (womb adulthood): Determines shape Remodeling (adulthood): Maintains bone integrity through resorption and formation Peak bone density reached before the age of 30 ; decreases after age of 40 Dual Energy X-ray Absorptiometry (DEXA) o Non-invasive o Measures bone density with low level X-ray o Results compared to average healthy 30-year old o T-score used for risk of fracture or osteoporosis o Recommended for postmenopausal women Calcium absorption requires vitamin D; enhanced by acid environment o Forms and maintain bones and teeth o pH balance o Transmission of nerve impulses o Muscle contraction o Promotes weight loss o Regulates hormones and enzymes o Maintains blood pressure, initiates blood clotting 1
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Adequate Intake (AI) for calcium is 1,000 mg to 1,300 mg per day Bioavailability –ability to absorb and utilize calcium depends on: o Age and need for calcium o Amount of dietary calcium and vitamin D o Binding factors (phytates, oxalates) in foods Calcium found in yogurts, milk, collard greens, cheese Vitamin D o Fat-soluble o Stored in liver and adipose tissue o Synthesized from exposure to UV light o Considered a hormone since it is synthesized in one location and acts in another location o Required for calcium and phosphorus absorption from the small intestine 2
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o Regulates blood calcium levels o Works with PTH to stimulate osteoclasts o Necessary for bone calcification o No RDA for vitamin D o AI ranges from 5 – 15 μg/day (assumes sun exposure is inadequate) o Sources of vitamin D: Ergocalciferol (D2) – plants, supplements Cholecalciferol (D3) - animal foods, sun Most foods contain little vitamin D Mostly obtained from fortified foods (milk, soy) Hypercalcemia (high blood calcium from too much vit D) Too little vit D Rickets (in kids), Osteomalacia (in adults) Vitamin K Fat-soluble; stored in the liver Blood coagulation Bone metabolism Phylloquinone – plant form of vitamin K (green leafy veggies, vegetable oils) Menaquinone – form of vitamin K produced by bacteria in large intestine No RDA AI 120 μg/day for men and 90 μg/day for women Phosphorus Major intracellular negatively charged electrolyte (phosphate) Critical to mineral composition of bone Proper fluid balance Component of ATP, DNA, membranes RDA is 700 mg/day Found in protein-containing foods (milk, meats, eggs) o In processed foods as a food additive o In soft drinks as phosphoric acid 3
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Magnesium 50 – 60% found in the bones Cofactor for over 300 enzyme systems Required for ATP, DNA, and proteins Supports vitamin D metabolism, muscle contraction, and blood clotting 310 mg/day for women age 19 – 30
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This note was uploaded on 04/21/2008 for the course HNF 150H taught by Professor Rosmos during the Spring '07 term at Michigan State University.

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Exam 3 Review Guide - Bone Health Strength, flexibility 65%...

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