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EXB 117 FINAL > 9-10. Sarcopenia > Flashcards

9-10. Sarcopenia Flashcards

1
Q

By what mechanism does muscle atrophy and weakness affect every person in their lifetime?

A

Aging

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2
Q

Define sarcopenia.

A

Age-associated loss of skeletal muscle mass and function

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3
Q

What % muscle loss defines sarcopenia? Age ranges?

A

Loss of 1-2% of lean mass per year after the age 50, w/ accelerated loss after age 65

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4
Q

The regulation of skeletal muscle involves a balance b/t what 2 processes?

A

Protein synthesis vs. Protein degredation

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5
Q

What are the sequential pathways that regulate muscle growth and atrophy throughout life?

A
  1. Myogenesis
  2. Postnatal growth
  3. Adult maintenance and adaptation
  4. Aging
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6
Q

What differentiates b/t adult maintenance and aging w/ regards to atrophy & hypertrophy?

A
  • Adult maintenance and adaptation = change in fiber size, but not # of fibers
  • Aging = change in both fiber size and number
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7
Q

What stressors contribute to muscle growth and atrophy?

A
  • Load
  • Neural activity
  • Growth factors and hormones
  • Inflammation, cytokines
  • Metabolic stress
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8
Q

Why should peeps care about sarcopenia? What are the consequences of this disease?

A

Relationship b/t loss of muscle and:

  • loss of independence
  • nursing home admissions
  • increased incidence of falls and fractures
  • increased mortality
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9
Q

In general, what % loss of capacity limits normal functioning? Results in failure?

A
  • 30% limits normal functioning

- 70% results in failure

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10
Q

What are the stages of muscle mass maintenance over a lifetime?

A
  1. Early life: Growth and development to maximize peak
  2. Adult life: maintaining peak
  3. Elderly life: minimizing loss
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11
Q

What does the frailty threshold on a functional capacity vs. age graph signify?

A

Reduced functional capacity and increased potential for injury

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12
Q

What causes the significant loss of muscle CSA seen in sarcopenia?

A
  • loss of muscle fibers
  • loss of fiber area
  • increase in the amount of fat and connective tissue w/in the muscle
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13
Q

Do we see a greater decrease in type I or II muscle fibers loss as a result of sarcopenia?

A

Type II (fast) fibers

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14
Q

How does sarcopenia affect muscle strength?

A

Decrease

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15
Q

How does sarcopenia affect muscle twitch?

A

Smaller and slower contraction

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16
Q

What factors account for the slowing of muscle contraction time?

A
  • Loss of sarcoplasmic volume and Ca2+ pumping capacity w/ aging
  • Decrease in density of dihydropyridine receptors (DNPR)
17
Q

How does sarcopenia affect muscle force and power?

A

Decrease

18
Q

How does sarcopenia affect specific force?

A

No change

19
Q

As peeps age, how does the relationship b/t muscle mass and force output change? Significance?

A

Relationship becomes weaker:

  • muscle strength is lost faster than muscle mass
  • gaining mass doesn’t prevent aging-related strength loss
20
Q

How do motoneuron and motor units change w/ age?

A
  • decrease in # of motoneurons
  • Increase in size of motor units due to collateral sprouting
  • delayed regeneration of injured motor axons w/ aging
21
Q

What is the significance of motor units increasing in size w/ aging?

A

Decreased capacity for fine motor skills

22
Q

What is collateral sprouting?

A
  1. Neurons become denervated
  2. Axons close to them have to sprout and innervate those fibers
  3. Motor units become larger
  4. Fibers group by type (slow vs. fast)
23
Q

What is the rate limiting step of protein synthesis?

A

Initiation

24
Q

How do the elderly show a “resistance to anabolism”?

A

As we age, the same level of loading results in less protein synthesis or muscle hypertrophy

25
Q

How much muscle mass can a sedentary person expect to lose b/t ages 20-60? 60-80?

A
  • 20-60 = 20-25%

- 60-80 = 20-25% more

26
Q

Which segments of the population are most at risk for clinically significant sarcopenia? How does this compare w/ segments of the population that are most likely to participate in resistance training?

A
  • Elderly = less likely to participate in resistance training –> increased sarcopenia risk
  • Young = more likely to participate in resistance training –> decreased sarcopenia risk
27
Q

By what mechanisms do physical activity maintain brain function?

A
  • Increased neurogenesis (esp in hippocampus)

- Increased brain-derived neurotrophic factor

28
Q

Why is the combo of sarcopenia and osteoporosis in the elderly a “recipe for disaster”?

A

Increased risk of injury and mortality

29
Q

What is dementia?

A

Deteriorated mental state w/ reduction in intellectual faculties due to organic brain disease

30
Q

Which type of studies (methodologically) provide the best data to support the idea that senility is a hypokinetic disease?

A

Longitudinal studies following how a brain changes in the course of exercise training

EXB 117 FINAL (4 decks)

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