Bone and it's function

1. MUSCULAR SKELETON SYSTEM :
NUTRITION AND BONE,BONE
MINERAL DENSITY

2. INTRODUCTION
• The musculoskeletal system is made up of bones, cartilage, ligaments, tendons
and muscles, which form a framework for the body.
• Tendons, ligaments and fibrous tissue bind the structures together to create
stability, with ligaments connecting bone to bone, and tendons connecting muscle
to bone.
• There are 206 bones in the adult skeleton.
• male and female skeletons are almost the same

3. NUTRITION
• Bone Provides Strength and flexibility
• Contains about 65% mineral ,providing the hardness of bone
• Contain 35% organic structure for strength, durability and flexibility
[collagen]
• Hydroxyapatite: mineral crystals around collagen designed to bear weight

4. NUTRITION FOR BONE HEALTH
• Calcium is the most recognized nutrient associated with bone health
• Also essential for bone health :
Vitamins D and K
Phosphorus
Magnesium
Fluoride

5. CALCIUM
• Calcium absorption
Is enhanced in an acid environment
Requires 1,25-dihydroxyvitamin D

6. FUNCTIONS OF CALCIUM
• Provides Structure for bone and teeth
• Assists with acid –base balance
• Assists in transmission of nerve impulses
• Assists in muscle contraction
• Initiates blood cloating

7. CALCIUM INTAKE
• Adequate intake varies with age and gender : 1,000 mg to 1,300mg/day
• Upper Limit :2500mg
• Bioavailability : Body’s ability to absorb and utilize calcium depends on
Individual’s age and calcium need
Dietary calcium and vitamin D
Binding factors (Phytates, Oxalates)in foods

8. SOURCE OF CALCIUM
Excellent sources include milk products
 Skim milk , low fat cheese ,nonfat yogurt
Other good sources include
 Green leafy vegetables (kale ,collard greens, broccoli and cabbage are low in
oxalates )
 Fortified foods(orange juice , soy milk)
 Fish with edible bone (sardines , salmon)

9. VITAMIN D
• Fat soluble vitamin
• Excess is stored in liver , adipose tissue
• Can be synthesized by the body from exposure to UV rays from the sun
• Considered a hormone ; synthesized in one location and regulates activities in
other parts of the body

11. FUNCTIONS OF VITAMIN D
• Regulates blood calcium levels
• Stimulates osteoclasts when calcium is needed elsewhere in the body
• Required for bone calcification
• May decreases cancer growth
• Involved in cell diffrentiation

12. VITAMIN D INTAKE
• RDA :600 IU for men/women ages 19 to 70 ; 800 IU for adults over age 70
• UL : 4000 IU for everyone 9 years of age
• Controversy : Recent evidence suggests that the current RDA is not sufficient to
maintain optimal bone health and reduces the risks and for disease such as
cancer

13. SOURCES OF VITAMIN D
• Ergocalciferol (D2) : Plants , supplements
• Cholecalciferol (D3) : Animal Foods and sun
Most foods naturally contain little vitamin D
 Most obtained from fortified foods(eg: milk)
High amounts : cod liver oil , fatty fish (salmon)

14. VITAMIN K
• Fat soluble vitamin stored in the liver
• Phylloquinone : Plant form (dietary) of vitamin K
• Menaquinone : animal form of vitamin k produced by bacteria in the large
intestine
• Vitamin K functions as coenzyme : - Blood Coagulation , Bone Metabolism

15. VITAMIN K INTAKE
• Recommended Intake
AI values are 120 /day for men and 90 /day for women
• Sources of VITAMIN K
Synthesized by bacteria in the large intestine
Green leafy vegetables (Spinach , Collard greens , Kale , Lettuce)

16. PHOSPHORUS
• Phosphorus is the major intracellular negatively charge electrolyte
Functions
Critical Bone formation
Required for proper fluid balance
Component of ATP , DNA , Membranes

17. SOURCES OF PHOSPHORUS
• High on protein containing foods such as milk , meats , eggs , legumes
• In soft drinks as phosphoric acid

18. MAGNESIUM
• Kidneys regulate blood magnesium levels
Functions
Mineral found in bone structure
Cofactor for over 300 enzymes systems
Required for ATP , DNA and Proteins

19. FLUORIDE
• Trace mineral . Stored in teeth and bones
Functions
Develop and maintain teeth and bones
Combines with calcium and phosphorus to protect teeth from bacteria
Stimulates bone growth

20. • Recommended Intake
AI varies by gender and increase with age , ranging from 1 to 4mg/ day
• Sources
Fluoridated dental products
Fluoridated water (not in bottled water)

21. BONE MINERAL DENSITY
• Strong bones are important for your health. A bone mineral density (BMD) test is
the best way to measure your bone health. It compares your bone density, or
mass, to that of a healthy person who is the same age and sex as you are. It can
show:Whether you have osteoporosis, a disease that makes your bones weakYour
risk for breaking bonesWhether your osteoporosis treatment is working

22. • Low bone mass that is not low enough to be osteoporosis is sometimes called osteopenia.
• cause of low bone mass include family history, not developing good bone mass when you
are young, and certain conditions or medicines.
• Not everyone who has low bone mass gets osteoporosis, but they are at higher risk for
getting it.
• If you have low bone mass, there are things you can do to help slow down bone loss.
• These include eating foods rich in calcium and vitamin D and doing weight-bearing
exercise such as walking, tennis, or dancing. In some cases, your doctor may prescribe
medicines to prevent osteoporosis.

23. • Bone density testing can be done in several ways.
• The most common and accurate way uses a dual-energy x-ray absorptiometry
(DEXA) scan.
• DEXA uses low-dose x-rays. (You receive more radiation from a chest x-ray.)

24. • There are two types of DEXA scans: Central DEXA -- You lie on a soft table.
• The scanner passes over your lower spine and hip. In most cases, you do not
need to undress.
• This scan is the best test to predict your risk for fractures, especially of the hip.
Peripheral DEXA (p-DEXA) -- These smaller machines measure the bone density
in your wrist, fingers, leg, or heel.
• These machines are in health care offices, pharmacies, shopping centers, and at
health fairs.

25. • Normal BMD
A T score of -1 to +1 is considered normal bone density.
 A T score of -1 to -2.5 indicates osteopenia (low bone density).
 A T score of -2.5 or lower is bone density low enough to be categorized as
osteoporosis.

26. FACTORS AFFECTING BMD LEVELS
Age and Sex
• Aging causes changes in cortical bone microstructure and higher bone porosity,
and age correlates negatively with BMD and bone strength. Fragility is the result
of bone loss and degradation of bone structure.
• Assessment of haversian canal and osteon area produced by an increase in
osteon-remodeling rates with age indicates an increase in intracortical porosity,
which may be used as an indicator for the diagnosis of osteoporosis and age-
related risk of fracture.

27. ANCESTRY AND HERITABILITY
• Molecular studies have shown a link between osteoporosis and genes responsible for
the regulation of bone metabolism, with a close correlation between the disorder and
the vitamin D–receptor gene.
• Studies showed that femoral bone strength and BMD for black ancestral groups were
greater compared to white groups. White American females demonstrated a higher
prevalence of osteoporosis and low BMD in comparison with their male counterparts
and black females. In white females, fracture risk corresponds to maternal family
history, suggesting a genetic predisposition for higher fracture risk and lower BMD.

28. LIFE STYLE
• Genes and environment interact influencing bone metabolism. Individual habits,
such as diet, exercise, alcohol intake, and smoking, also have an impact on BMD.
• A positive relationship between mechanical strain and BMD has long been noted.
BMD changes in response to loading exhibit variation depending on the type,
duration, intensity, and frequency of physical activities.

29. TRAUMA
• The ability of skeletal elements to resist applied forces is linked to bone
mineralization, a primary determinant of strength and stiffness in compression.
While higher mineralization increases these properties, it will also increase bone
brittleness, thereby decreasing toughness and augmenting the risk of bone
trauma.
• In addition to BMD, bone resistance to fracture is shaped by other structural and
microstructural properties like cortical thickness, cross-sectional area, moment of
inertia, cortical porosity, and microcracks.

30. CONTINUED…
• Another complication associated with fragility and bone fracture might be
systemic bone loss after fracture, as witnessed in experimental and clinical
studies. In limb fractures, BMD within the injured limb decreases after fracture
from 3% to 31% compared to baseline values measured close to the time of
fracture.67–70 This is a result of reduced formation of bone following fractures
while resorption levels either remain unchanged or increase.