Osteoperosis Flashcards
Rickets/Osteomalacia (2)
Vitamin D deficiency leading to softening of bones
Because of inadequate bone mineralisation
Why do osteoporotic fractures increase during winter?(2)
Lower sunlight exposure
Reduced vitamin D synthesis
Osteoporosis (3)
Low bone mass
Deterioration of bone tissue
High risk of fracture
Alcoholism (4)
Suppresses proliferation of osteoblasts which inhibits born formation
May increase osteoclastogenesis
Reduced bone mineral density
Increased risk of falling
Reproductive cycle and risk of osteoporosis
Early menopause or late menarche increase risk
Types of bone material (2)
Cortical
Trabecular
Most common bone material
Cortical (70-80%)
What is the majority of skeleton made from?
Inert matrix materials
Inert matrix materials (3)
Calcium
Phosphate
Collagen fibres
When does the deposits of matrix occur?
Childhood
What is peak bone mass?
Maximum bone mineral mass attained
Role of osteoblasts
Bone mineral deposition
Role of osteoclasts
Bone mineral loss
Growth hormone
Increases osteoblasts
Vitamin D3 effects (5)
Increases calcium absorption
Increases calcium uptake
Increases calcium bone deposition
Also increases osteoclasts
Results in calcium bone loss
Calcitonin
Inhibits osteoclasts
Sex steroids
Increases osteoblasts
Increased deposition
Parathyroid hormone (4)
Inhibits sex steroids (prevents osteoblasts)
Increases osteoclasts
Bone loss
Calcium bone loss
______ bone remodels ____ times faster than _____ bone
Trabecular
8
Cortical
Which bone regions are more vulnerable to bone loss?
Trabecular
Role of VDR (2)
Role in controlling calcium status
Variants linked to lower BMD
Oestrogen receptor (2)
Key role in oestrogen effects on bone tissue
Variants may be linked to BMD
Collagen 1 alpha 1 gene (2)
Collagen 1 alpha is the main protein in bone
Abnormal gene forms may alter bone and reduce strength
What percentage of gene variation may related to BMD
60-90%
Importance of childhood
Maximising peak bone mass
Importance of young adulthood
Maintain bone mass
Importance of older adulthood
Minimise bone loss
Calcium (4)
Benefits bone health at any stage
Higher intakes increase bone mass
However does but reduce the risk of fractures
Benefits of supplements disappear rapidly once supplementation ends
Effects of vitamin D supplementation (2)
Reduces risk of fractures at high doses
Slows bone mineral loss in individuals with low calcium status
Caffeine and BMD (5)
Associated with lower BMD
Promotes excretion of calcium
Reduced calcium uptake from gut
In post menopausal women high intakes may be related to increased risk of fractures
VDR genotype dependent
Phytoestrogens (5)
Plant derived agents with similar structure to steroids
Can bind to oestrogen receptors and produce biological effects
May be safe alternative to HRT post menopause
May prevent bone loss in women
However studies have shown little effect
Equol (4)
Produced by gut microflora after consumption of phytoestrogens
Depending on phenotype
This conversion more prevalent in vegetarians
Has enhanced effects at oestrogen receptors
Protein and osteoporosis (4)
Excessively high intakes may promote calcium excretion and bone loss
Protein promotes muscle strength and reduces risk of falls
Moderate intakes increases BMD depending on calcium status
However elderly are at the greatest risk of PEM in developed countries
