The ageing skeleton Flashcards
What is sarcopenia Latin for
povert of the flesh
What is sarcopenia
Used to describe inevitable loss of muscle mass and strength that occurs in ageing muscle, even in the healthy elderly
What is important about muscle gaining and age
Muscle gaining will not prevent loss of muscle mass
What are one of the easiest ways of measuring strength
Hand grip
What is isometric strength
Strength when the muscle is not changing shape
Compare rate of loss of force and reduction in muscle area
Loss of force is greater than reduction in area
What happens to motor units through age
Effect?
Fewer fast motor units Slow motor neurons sprouting Motor units become denervated by slow motor neurons making them into slow motor units More fibres per motor unit less muscle fibres atrophy More slow muscles slow muscle reflexes Poor coordination Increase risk of falls
What is a motor unit
A. motor unit is the term applied to a single motor neuron and all of the muscle fibres that it stimulates
What factors contribute to sarcopenia
Nutritional
Hormonal
Immunological
Physical activity less activity
What leads to sarcopenia
loss of motor units increase in muscle fibres muscle fibres atrophy which leads to: loss of muscle mass loss of muscle strength
What does sarcopenia mean for patients
Weakness and decreased mobilty
What does sarcopenia lead to
disability and loss of independence
How does sarcopenia lead to dependency 5
Loss of muscle mass Loss of muscle strength Decreased physical activity Increase risks of fall Loss of autonomy
How is osteopenia characterised?
bone loss
reduced bone mineral density (BNAD)
micro-architecture deterioration
What happens with patients with osteopeania
Bones become more fragile
What percentage of men and women are affected by osteopaenia?
50% women
30% men
What area of the body of most at risk of osteopenia
Vertebrae
hip
wrist
What important aspect of fractures?
Previous fracture increases risk of future fracture
How is osteopania defined/diagnosed
By the T-score
What calculates a T-score
DEXA
What does DEXA stand for
dual energy X-ray absorptiometry
What measures bone density/ bone loss
DEXA
What does DEXA measure
bone loss
What T-score is classified as osteopenia
-1- -2.5
What T-score is classified as osteoporosis
LESS than -2.5`
What T-score is classified as normal
more than -1
How does cortical bone strength decrease over time (rate)
by 2 % per decade from 20 years old
How does toughness decrease over time
by 7% per decade
What type of bone is affected more due to ageing and why
trabecular bone affected more than cortical due to thinning and
loss of trabeculae
How does hormone affect bone and what happens with ageing
stimulate bone formation
hormone levels decreases, with age (men too!)
hormones also affect bone via muscle!
How does menopause effect bone strength? how is it treated?
menopause: bone loss becomes twice as fast in
women
effect is systemic (so other factors operate)
hormone replacement therapy (HRT) reverses
some of effects of menopause
Out of diet genes, hormones, and
exercise which has the least effect on bone density
diet has less effect than genes, hormones, and
exercise
How does ageing affect fibrous tissue
Cell content/ morphology changes
Collagen cross-links increase and mature (become
non-reducible)
Cross-links increase tissue strength & stiffness and brittle
Non-enzymic glycation (NEG) makes tissue yellow
and stiffer
Microdamage accumulates and makes tissue weaker
Cells become less responsive to mechanical stimuli - growing for example
NEG uncontrolled by cells: problem in tissues with low turnover
What causes bone to be more brittle?
Increase in cross links
What are the two main crosslinks
deoxypyridinoline
pyridinamine
How are does collagen crosslinking become the cause of stiffness and brittleness
Collagen molecules normally linked with crosslinks
But normal crosslinks are changed by non-enzymatic glycation which makes them sticky
less flexible
more brittle
What is non-enzymatic glycation
When a reducing sugar is added to a protein without using an enzyme
What are two types of tendon cells
Elongated cells - long processes - fat fibroblasts
thin tenocytes/fibrocytes
Where do you find elongated tendon cells
Immature tissue
Where do you find thin tenocytes tendon cells
mature tissue
What happens to tendons throughageing
Tendon thins becomes harder less flexible
What happens to ligaments with age?
Become stiffer
Age-related change in cartiladge
less proteoglycan content
less aggregation of PG’s
increase collagen content and cross-linking
increase levels of non-enzymatic glycation
increase apoptosis
increase stiffness
Cartilage cell density decrease with age
Chondrocytes stop dividing at skeletal maturity
Age related changes in spine
Disc degeneration
Stages of disc degeneration
annulus fibrosus looks hydrated
nucleus pulposus more jelly like
loss of hydration of the nucleus pulposus becomes more solid in older people
discolouration of white annulus fibrosus due to non- enzymatic glycation
may become damaged, and prolapse.
In very old tissue Damage to annulus fibrosus (outer layer)
pressure has changed as a result and softer inner pulposus can actually leak out through the damaged outer layer and pushes on nearby nerves leading to the pain associated with this
Damaged intervertebral disk- no nucleus pulpous change in overall structure
Overtime-
tissue becomes more fibrous
What is annulus fibrosus
the tough circular exterior of the intervertebral disc
What is nucleus pulposus
Inner core of the invertebra disk
What happens with vertebral osteoporosis
Trabecula thining
more porous
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What does vetebral osteoporosis lead to? What does that do?
Vertebral osteoporosis fracture leads to kyphotic deformity
