Lecture 9 - Bone Health

Bone Purposes: 7

1. Provide structure

2. Protect organs

3. Anchor muscles (via tendons)

4. Store calcium 

5. Regulates blood pH

6. Bone marrow → blood cells 

7. Cartilage: cushions bones at joints

Osteoblast

Cells responsible for bone formation

importance of building bone before breaking it down

higher number than osteoclasts in individuals under 28 years old.

Osteoclast

Cells involved in bone resorption, which is the recycling process of bone

• more active than osteoblasts after the age of 28, leading to a higher risk of osteoporosis and fractures.

name of mature bone cell

osteocyteage

Bone Mineral Density (BMD)

The measure of bone density, influenced by factors like gender, age, and hormonal balance, with men typically having higher BMD due to larger bones.

age of peak bone mass 28

Men vs women: BMD

men have higher BMD due to larger bones (therefore have denser bones ot support larger overall body)

hormones that affect BMD

Estrogen and testosterone

stages of BMD acquisition

• Modelling: 0-28 y.o.

• Peak bone mass: 28 y.o. 

• Remodelling: >28 y.o - gradual bone loss 

2 key components of BMD:

1. Vit D

2. Calcium

Vitamin D

Essential for calcium absorption, can be synthesized by the body when exposed to sunlight

• food sources like cheese, fortified milk, mushrooms, and tofu.

Calcium

Vital for bone health, with recommended daily intake varying by age and sex

• sourced from dairy products like milk and cheese, as well as non-dairy options such as beans, figs, and broccoli.

Physical Activity

Weight-bearing exercises and activities are crucial for bone health, stimulating bone growth and adaptation, with impact activities like jumping being particularly beneficial.

Vit D RDA

600 IU/day for all ages and sex, except 800 IU/day for >70 y.o

Calcium Rx/ RDA

Both sex, 9-18 y.o: 1300 mg/ d

Both sex, 19-50: 1000 mg/ d

Males, 51-70: 1000 mg/ d

Females, 51 to >70: 1200 mg/ d

Males, >70: 1200 mg/ d

Osteoporosis

A condition characterized by weakened bones, increasing the risk of fractures, with preventive measures including a balanced diet, adequate calcium and vitamin D intake, and regular exercise.

caffeine, sodium, and calcium

Ca and Na increase calcium excretion via urine

Salty Six

high sodium foods:

1. Cold cuts and cured meats

2. Poultry

3. Bread and rolls 

4. Soup

5. Sandwiches 

6. Pizza

Bone Density Scan

A diagnostic test using low-dose X-rays to assess bone health, detecting mineral loss and thinning, recommended for individuals at risk of osteoporosis due to factors like age, family history, or medication use.

PA will only affect bone at the skeletal sites that:

are stressed (or loaded) by the activity

For bone gain to occur, the stimulus must be

greater than that which the bone experiences

• Static loads applied to muscle (such as standing) do not promote increased bone mass

Complete lack of activity (immobility, paralysis, bed rest) causes bone __________

loss

PA most days of the week, coupled with ________, ______, and __________ for _______time a week, is effective for promoting bone health for most people

weight bearing, strength building, and balance-enchanting activities

2 or more x/ wk

Any activity that causes _______________ may increase bone mass more than ________________ enducrat-type activities

impact (ex. Jumping, skipping) ;

low- to moderate-intensity

T/F: Load-bearing physical activities (ex. Jumping or skipping) need to be engaged in for long periods of time to provide benefits to skeletal health

F: don’t need to spend long

PA should include a variety of _________ ____________ to promote increased bone mass.

loading patterns

__________ women and _______ men over 50 will experience osteoporosis fracture

1. 1 in 3

2. 1 in 5

Risk factors: osteoporosis (4)

1. Genetic susceptibility

2. Inactive lifestyle

3. Age (over 45) insufficient mass

4. Growth 

Bone measurement method

Bone density scan

• a low dose x-ray which checks an area of the body such as the hip, hand, or foot for signs for mineral loss and bone thinning

stages/ progression osteoporosis

Healthy → Osteopenia → osteoporosis 

• >2 SD= osteoporosis Who needs a bone density scan

Who needs a bone density scan

• rx for everyone at risk for osteoporosis or another condition

  • Long-term use of corticosteroids

  • Hormonal imbalance

  • Excessive consumption of alcohol

  • A fam. hx of osteoporosis

  • Low or high body mass

  • Smoking