Muscle L3: Ageing and Rehabilitation Flashcards
What is ageing?
natural changes in an adult which compromise its ability to survive
There is a difference in muscle volume and physical strength between men and women continues throughout the life span. True or false?
True
Physical activity also lower in women than men throughout adulthood. True or false?
True
There is a difference in muscle volume and physical strength between men and women continues throughout the life span. True or false? Peak strength at around 25 for both men and women but increased difference in peak strength. True or false
true; true
What is sacropenia?
Loss of lean body mass & muscle weakness associated with advancing age ‘… ageing or pathological states, as well as environmental factors (nutrition, physical activity/ mechanical stress) may influence muscle and bone simultaneously’
What are 5 strong predictor for muscle strength?
- severe mobility limitation
- slow gait speed
- increased fall risk
- risk of hospitalization, and high mortality rate.
The interactions between _____ and ____, might be very important for understanding the physiology and pathophysiology of sarcopenia and osteoporosis.
muscle; bone
The aging-associated loss of muscle mass: coincides with the onset of _____ in women; accelerates during the transition into menopause; then proceeds slower in women than in men
menospause
The age-associated decline in muscle mass affects everyone, even master-athletes. True or false?
True
While losing lean body mass, an ‘average’ adult will gain approximately 1 kg of fat per year between 30-60 years. True or false?
False
- Will again approximately 0.5kg
The modification in body composition is frequently masked by unchanging body weight. True or false?
True
What 3 factors accelerate the process of sarcopenia?
- Advanced age (80 yr and older)
- periods of inactivity
- disease
What are 2 neural factors that contribute to sarcopenia?
- Changes in central nervous system drive (optimising neural drive comes with use/practice)
- Altered neuromuscular junction structure and function (whether changes in the NMJ precede or follow the decline of muscle mass and strength remains unresolved)
What are 7 changes in the musculotendinous unit with ageing?
- Muscle fibre
- Fibre type transformation
- Myofilaments
- Mitochondria
- Adipocyte infiltration
- Excitation-contraction coupling
- Satellite cells
What are 2 changes that occur in muscle fibre in the musculotendinous unit with ageing?
- decreased in number
- decreased in size (predominately type II)
What is a change that occur in fibre type tranformation in the musculotendinous unit with ageing?
- Fast –> slow fibre type shift
What are 3 changes that occur in the myofilaments in the musculotendinous unit with ageing?
- reduced single fibre maximal force
- reduced in myosin protein content and function
- reduced in elasticity
What are 2 changes that occur in the mitochondria in the musculotendinous unit with ageing?
- Decreased number
- Loss of enzyme content
What is a change that occur in adipocyte infilratation in the musculotendinous unit with ageing?
- increased inter- and intra-muscular adipose tissue
What are 2 changes that occur in excitation-contraction coupling in the musculotendinous unit with ageing?
- Disruption or uncoupling
- Deficits in Ca2+ release
Satellite cells maintain ______homeostasis and enable skeletal muscle ______.
skeletal muscle; regeneration
Satellite cells maintain ______homeostasis and enable skeletal muscle ______.
skeletal muscle; regeneration
Satellite cells are stimulated by ____ or _____ to muscle tissue
damage; stress
Close to the muscle fibres, satellite cells (stem cells that can differentiate into myoblasts) sit within _______.
endomysium
______ fuse to other muscle cells during growth and repair throughout the life-span
Myoblasts
With ageing, muscle tissue homeostasis is progressively disrupted and the ability of muscle stem cells to repair injured muscle markedly _______.
declines.
What are 4 stages of the satellite cell cycle?
- Satellite cells can fuse to form new muscle fibers or self-renew and replenish the satellite cell pool, that will be used in the future
- age-related decline in satellite cell function compromises recovery capacity of sarcopenic muscles in response to injury
- satellite cell number loss contributes to agedependent muscle fibrosis (excess fibrous connective tissue)
- Greater reduction of satellite cells in type II (fast) fibers – large force, fatigue resistant fibres o If damage type II fibres, less able to repair compared to type I
Greater reduction of satellite cells in type____(fast) fibers – large force, fatigue resistant fibres
Type II
The reduction in muscle fiber size is fiber type specific, with 10%–40% smaller type II fibers in elderly compared with young. True or false?
True
Type I muscle fiber size is largely unaffected. True or false?
True
Motor neurons die with increasing age. True or false?
True
There is denervation of type II muscle fibers with collateral re-innervation of type I muscle fiber neurons. True or false?
True
Young adulthood is characterized by an intermingling of fibres belonging to different motor units. True or false?
True
Adulthood to old age is characterized by ____________that result in fibres of the same type being beside one another (fibre type grouping) when viewed in cross-section.
repeating cycles of denervation-reinnervation
Very old age is characterized by _____ frequency of axonal degeneration and/or motor neuron death leading to ________ when viewed in cross-section. In particular denervation of type II muscle fibers with collateral re-innervation of type I muscle fiber neurons
increasing; grouped fibre atrophy
Explain the process of muscle contraction
• There are receptors in the T-tubule which are needed to activate calcium release from the sarcoplasmic reticulum. • Once calcium is released, it binds to troponin C and allows actin-myosin cross bridging • Calcium is then pumped back into the sarcoplasmic reticulum • Aging is associated with a reduction in # of receptors in the T-tubule and therefore deficits in calcium release • Structural alterations of myosin (reduction in myosin protein content) o Reduces total # actin-myosin cross-bridges o Greater % of cross-bridges in a weakbinding state
Muscle contraction: Step 1: There are receptors in the T-tubule which are needed to activate calcium release from the __________.
sarcoplasmic reticulum
Muscle contraction: Step 2: Once calcium is released, it binds to ______ C and allows ____________ to occur
troponin; actin-myosin cross bridging
Muscle contraction: Step 3: ______ is then pumped back into the sarcoplasmic reticulum
Calcium
Muscle contraction: Ageing is associated with a reduction in # of receptors in the ______ and therefore deficits in _______.
T-tubule; calcium release
Muscle contraction: What are 2 things that structural alterations of myosin (reduction in myosin protein content) affect?
- Reduces total # actin-myosin cross-bridges
- Greater % of cross-bridges in a weakbinding state
With ageing, there is a ______ in stiffness (reduction in elasticity) reported in whole muscle as well as in single fibers.
increased
Ageing alters titin properties. True or false?
True
What are 3 changes in the connective tissue ECM?
o Decreased collagen turnover o Buildup of collagen crosslinks o Stiffening of the epimysium
Altered elasticity may expose the collagen of skeletal muscle to ______ or _____. Also may alter transmission of ______ muscle force to the tendons.
deformation; rupturing; tensile
Mitochondria are the main producer of ________.
cellular energy (ATP)
Mitochondria lie ______ the muscle cell.
within
With ageing, mitochondria is ____ and has ________ enzyme (use oxygen to produce ATP).
smaller; reduced oxidative enzymes
The number # of Type I muscle fibres _______ (does/doesn’t) decrease with age,
Doesn’t
Efficiency ______ (is/isn’t) due to reduced mitochondrial # & morphology with age
WiIll
Ageing is associated with increases in both intra- and inter-muscular adipose tissue. True or false?
True
Ageing’s reduced muscle mass is replaced by _____and this will influence _______.
Fat; pennation angle
Ageing reduce fascicle length and that in turn reduces _________ and ________.
sarcomeres in series # cross bridges
_______ in skeletal muscle is associated with both metabolic and mobility impairments in older individuals.
Fat infiltration
Bed rest and microgravity conditions lead to losses of both ______ and ______ volume
myofibrillar; mitochondrial
Immobilisation has no/little impact on muscles. True or false?
False
- Even short immobilisation periods can have massive effects. 2 weeks of immobilization reduces type I, IIa and IIx muscle fibre areas by 13, 10 and 10%, respectively
- Without regular exercise astronauts can lose up to 20% of their muscle mass in just 5 to 11 days
- Microgravity induces atrophy of both type I and type II fibres with evidence of a transition toward more type II fibers
_____ is the primary strategy in the prevention and treatment of sarcopenia.
Exercise
________ training in which the external load is systematically increased as the person is able to work against a heavier load optimises the increase in muscle mass and strength, and attenuates the development of sarcopenia in older people.
Progressive resistance
