ageing and skeletal muscle

Question 1

what 5 ways has medicine extended our life expectancy and how has each done this?

Answer 1

Better sanitation

antibiotics:
- decreased mortality from infectious diseases

pre/postnatal care:
- lowered mortality in childbirth/infant mortality

drugs:
- has made otherwise lethal diseases “chronic” in nature

assist devices:
- compensates for loss of physiological function

Question 2

what percentage of people ≥ 65 years experience:
- weight loss
- exhaustion
- low energy
- slowness
- weakness

Answer 2

weight loss:
- 17.5%

exhaustion:
- 15.5%

low energy
- 27.0%

slowness
- 43.2%

weakness
- 21.8%

Question 3

what is the “break” in the link between life expectancy and healthspan?

Answer 3

• life expectancy continues to rise, however parameters of healthspan have stagnated for decades

Question 4

what are 3 pro-aging factors in rate of ageing

Answer 4

• loss of renewal capacity
• hormonal changes
• Accumulation of damage (e.g reactive oxygen species)

Question 5

what are 2 examples of loss of renewal capacity as a pro-aging factor?

Answer 5

• loss of stem cells
• shortening of telomeres

Question 6

what are 5 longevity assurance systems for ageing

Answer 6

• DNA repair
• stress responses
• antioxidant defences
• protein and cell turnover (eg: muscle)
• mitochondrial maintenance

Question 7

Genome analysis

what are SNPs

Answer 7

changes in genes that does not alter the genetic code of the gene, but might adjust supplementary factors such as shape of the protein made from the gene etc

Question 8

hormesis

what is hormesis

Answer 8

stimulant that causes harm, but up to a point actually has a positive effect (known as the hormetic zone)

(eg: muscles cause oxidative damage that when in the hormetic zone can induce repair mechanisms to make muscle stronger)

Question 9

changes in muscle Mass with aging

what percentage of muscle mass is lost from age 20-70

Answer 9

40%

Question 10

changes in muscle mass with aging

what percentage of muscle mass is lost per decade from age 30-70

Answer 10

6% decline

Question 11

sarcopenia

define Sarcopenia

Answer 11

age associated loss in muscle mass

Question 12

fat and collagen infiltration

what 3 things can sarcopenia be associated with other than reduced muscle mass

think fat, death and function

Answer 12

• decreased muscle quality due to fat inflitration
• increased mortality
• functional decline

Question 13

what are the 3 forms of Fat inflitration

Answer 13

• subfascia
• intermuscular
• intramuscular

Question 14

ageing muscles: cross-sectional studies

what are 4 conditions/observations in ageing of muscle

Answer 14

• fiber loss via denervation and apoptosis (fewer fibers)
• fiber atrophy [particularly in type II muscle fibres] (smaller fiber cross-sectional area however is reversible)
• lower extremities>upper extremities
  e.g: Postural/locomotor muscles waste more than non-postural muscles
• rate of loss in males > females