NUTR 225 Ch. 9

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  1. Bone Structure
    • - Provides strength to support body
    • - Allows for flexibility
    • - Contains 65% minerals
    • - Contains 35% organic structures for strength, durability, flexibility
    • - Collagen: fibrous protein in bone tissue
  2. Two types of bone tissue
    • 1) Cortical bone (compact): very dense tissue make up 80% of skeleton
    • - Outer surface of all bones
    • - Many of the small bones

    • 2) Trabecular bone (spongy bone): "scaffolding" on the inside of bones; supports cortical bone and makes up 20% of skeleton
    • - Fast turnover rate
  3. Bone development processes (3)
    • 1) Bone growth: increase in bone size; age 14 for girls, age 17 for boys
    • 2) Bone modeling: shaping of bone; complete by early adulthood
    • 3) Bone remodeling: reshaping of bone; occurs throughout life
  4. Bone remodeling involves...
    • 1) Resorption: surface of bones is broken down
    • - Osteoclasts: cells that erode the surface of bones

    • 2) Formation of new bone by cells called osteoblasts
    • - Osteoblasts produce the collagen-containing component of bone
  5. Bone Density
    • - Peak bone density: Before age 30
    • - Remodeling maintains bone density
    • - Density decreases: after age 40
  6. Calcium
    • The most abundant major mineral in the body
    • - 99% of calcium found in bones
  7. Functions of calcium
    • - Forms and maintains bones and teeth
    • - Assists with acid-base balance
    • - Transmission of nerve impulses
    • - Assists in muscle contraction
  8. Low calcium level
    • - Parathyroid hormone (PTH) is released
    • - PTH stimulates activation of Vitamin D
    • - Causes kidneys to retain more calcium, Osteoclasts to breakdown bone, Stimulation of calcium absorption from intestines
  9. High calcium level
    • - Thyroid gland releases calcitonin
    • - Prevents calcium reabsorption from kidneys, Limit calcium absorption from intestines, Inhibit osteoclasts from breakdown down bone
  10. Recommended intake of calcium
    1000mg-1200mg/day in adults
  11. Bioavailability
    • degree to which a nutrient is absorbed
    • - Infants and Children: can absorb over 60%
    • - Pregnant: can absorb over 50%
    • - Healthy adults: can absorb 30%
  12. Too much calcium vs. Not enough calcium
    Too much: Excess calcium is excreted from body; hypercalcemia can by caused by cancer and overproduction of PTH

    Too little: Hypocalcemia can be caused by kidney disease or vitamin D deficiency
  13. Functions of Vitamin D in Bones
    • - Required for calcium/phosphorus absorption
    • - Regulates blood calcium levels
    • - Stimulates osteoclasts
  14. Recommended intake of vitamin D
    5-15mg/day for adults
  15. Too much vitamin D vs. Not enough vitamin D
    Too much: Occurs from vitamin supplements; hypercalcemia

    Too little: occurs with diseases that reduce intestinal absorption of fat and limited exposure to sunlight; Rickets; Osteomalacia
  16. Vitamin K, Two forms?
    Fat-soluble vitamin

    • 1)Phylloquinone: plant form
    • 2) Menaquinone: form of vitamin K produced by bacteria in large intestine
  17. Functions of vitamin K
    • - Blood coagulation
    • - Bone metabolism
  18. Too much vitamin K vs. Not enough vitamin K
    Too much: No side effects

    Too little: Reduce blood clotting, excessive bleeding; occurs w/diseases that limi absorption of fat in the small intestine
  19. Phosphorus
    Primary intracellular negatively charged electrolyte
  20. Functions of Phosphorus
    • - Critical to mineral composition of bone
    • - Required for proper fluid balance
    • - Component of ATP, DNA, and membranes
  21. Recommended intake of Phosphorus
  22. Too much phosphorus vs. Not enough phosphorus
    Too much: Excessive vitamin D supplements for consumption of too many antacids can cause muscle spasms, and convulsions

    Too little: very rare in healthy adults
  23. Magnesium
    Bones contain 50-60% of the body's magnesium
  24. Function of magnesium
    • - Cofactor for over 300 enzyme systems
    • - Required for production of ATP, DNA, and proteins
  25. Recommended in take for magnesium
    • 400 mg/day for men (age 19-30)
    • 310 mg/day for women (age 19-30)
  26. Too much magnesium vs. Not enough magnesium
    Too much: supplements can cause diarrhea, nausea, cramps, dehydration, cardiac arrest

    Too little: hypomagnesemia can result in low blood calcium and osteoporosis; muscle cramps, spams, nausea, weakness, confusion
  27. Fluoride
    99% of body's fluoride in teeth and bones
  28. Functions of fluoride
    • - Development and maintenance of teeth and bones
    • - Combines with calcium and phosphorus to make tooth enamel stronger, which protect from cavities
  29. Recommended intake of fluoride
  30. Too much fluoride vs. Not enough fluoride
    Too much: Fluorosis creates porous tooth enamel; teeth become stained and pitted

    Too little: dental cavities
  31. Osteoporosis
    • Disease characterized by
    • - low bone mass
    • - deterioration of bone tissue
    • - fragile bones -> bone fractures
    • - compaction of bone -> decreased height
    • - shortening and hunching of spine, dowager's hump

Card Set Information

NUTR 225 Ch. 9
2013-06-09 23:40:11
NUTR Nutrition 225

Nutrition 225 Final
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