Osteoporosis Flashcards
osteoporosis is characterized by _______ bone strength
decreased
osteoporosis is prevalent amoung _________ women
postmenopausal
this is a reduction in the strength of bone that leads to an increased risk of fractures. bone density 2.5 SD below the mean for young healthy adults
osteoporosis
true or false: incidence of fractures happen earlier in men in those with osteoporosis
false - happen earlier in women
true or false: nutrition and physical activity affects your bone mass production throughout life
true
what are some risk factors for osteoporosis
- prior fractures
- family history
- low body weight
- smoking/alcohol
- rheumatoid arthritis
- malabsorption diseases
- excess corticosteroids
- medications
true or false: genetics are very important in determining bone mass
true
the most important etiological factor in osteoporosis is ________ deficiency
gonadal steroid - estrogen deficiency that occurs after menopause accelerates loss of bone mass
a genetic locus on chromosome ___ is associated with high bone mass
11
what does a point mutation on the LRP5 gene do for bone mass?
allows for a high bone mass resistant to age effects
know the bone remodelling process
A. origination of BMU-LINING CELLS (basic molecular unit) CONTRACTS TO EXPOSE COLLAGEN and attract prosteoclasts
B. osteoclasts fuse into multinucleated cells that resorb a cavity. mononuclear cells continue resorption and prosteoBlasts are stimulated to proliferate
C. osteoblasts align at the bottom of the cavity and start forming osteoid
D. osteoblasts continue formation and mineralization. previous osteoid starts to mineralize.
E. osteoblasts begin to flatten
F. osteoblasts turn into lining cells; bone remodelling at initial surface is now complete, BMU is still advancing.
* see osteoporosis lecture, slide 9 for simplified version!
why are postmenopausal osteoporotic fractures often in the spine?
because osteoporosis fetes trabecular bone more so than other types of bone
the cytokine responsible for communication between the osteoblasts, other marrow cells and osteoclasts is ___________. this is a member of the TNF family, is secreted by osteocytes, osteoblast and certain cells of the immune system
receptor activator of nuclear factor kappa-beta ligand (RANKL)
the osteoclast receptor for RANKL is __________. activation of this is a final common path in osteoclast development and activation.
RANK
this is a regulatory factor produced by bone marrow derived stroll cells, and acts as a decoy recpeot for the RANKL system. it inhibits bone resorption and binds with strong affinity to its ligand RANKL, thereby preventing the binding of RANKL to RANK, which activates osteoclast formation and bone resorption
OPG (osteoprotegerin)
