U2 Lecture 7 Flashcards
- Describe how exercise can affect bone mass - Describe the mechanism by which mechanical stress leads to changes - Describe the mechanism by which mechanical stress leads to changes in bone mass - Define osteoporosis and identify the risk factors for development of the disease. Offer strategies for prevention of osteoporosis
Men vs. female total bone calcium
Women lose more bone calcium during their life because they go through metapause
Effect of exercise on bone
Bone changes in response to the stresses it encounters
- muscle pulling on bone -> joint reaction forces
- impact -> ground reaction forces
Spongy bone vs. compact bone
Spongy bone is more metabolically active- can respond to changes in mechanical loading more readily
The most likely sites of fracture are areas with high spongy bone content (hip, wrist, spine)
What is the goal of exercise?
To reach the fracture threshold later in life
Why do we exercise?
Early in life - increase peak bone mass
Later in life - prevent bone loss
other benefits: fall prevention, improved strength, improved balance and coordination
What happens when there is a mechanical force on the bone?
Force applied to bone is sensed by the osteocytes -> proliferation of osteoblasts -> bone formation greater than bone resportion in response to exercise
Define osteoporosis
Age related disorder characterized by decreased bone mass and increased susceptibility to fractures, often as result of decreased levels of estrogens
What causes reduced bone mass?
- any factor that stimulates bone resorption or inhibits bone formation (or both)
- osteoclast activity (bone resorption) > osteoblast activity (bone formation)
What are some osteoporosis risk factors?
Calcium/ vit. D deficiency, older age, menopause***, genetics, environment/ family history, sex (female)
What are the 3 major bone diseases?
Osteoporosis, osteomalacia and osteogenesis imperfecta
Define osteoporosis
A decrease in bone mass and density -> thin bones and high risk of fractures
- not caused by ratio of bone mineral to matrix
- not associated w pain unless w fracture
- Tests: bone scans and not blood tests
- Osteoporosis is a type of osteopenia
Define osteomalacia
Lack of vit. D and/or Ca2+ which causes decreased mineralization of newly formed bone matrix at sites of bone remodeling
Associated with achy bone pain
Define osteogenesis imperfecta
Congenital disorder that affects production of type 1 collagen due to genetic mutation
Brittle bones that fracture easily, often in childhood or adolescence
Pain with fractures
