Skeletal Muscle Ageing LT4 Flashcards

Question

What happens to Type 2 muscle fibre as our vascular system ages?

Answer 1

Vascular damage occurs and because Type 2 have less capillary density to start with there is a dramatic reduction of satellite cells in Type 2 fibres

Answer 2

More innervated myofibers means more can contract simultaneously

Answer 3

Voluntary movements are generated in the brain as motor commands They pass down the spinal cord (CNS) and out through motor neurones (PNS) Sensory feedback from the muscles and joints informs the brain about the movement, allowing for adjustments if needed

Answer 4

Age-related loss of muscle mass, strength, and function Characterized by a decline in muscle fibres, particularly the fast-twitch fibres responsible for quick, powerful movements

Answer 5

If there is clinical suspicion, or they score low in the questionnaire, then grip strength is measured If that is low then muscle mass is measured (DXA) this can confirm saropenia Finally, measure physical performance = gait speed, chair sit 5x, and Timed Up and Go test (TUG) Which can confirm severe sarcopenia

Answer 6

Functional mobility, including: Balance Walking ability Fall risk in the elderly

Answer 7

Body composition analysis to look at muscle mass

Answer 8

Age, Sex, Race, Occupation, Dominant hand Injury history and machine measuring difference

Answer 9

Type II muscle fibers can undergo a process called "innervation switching," where they adapt to changes in motor neuron input. When fast-twitch fibers lose their innervation or experience motor neuron damage, adjacent motor neurons may reinnervate these fibers, potentially converting them to a slower, more fatigue-resistant phenotype. This process is facilitated by the plasticity of muscle fibers and the ability of satellite cells to support repair and remodeling. As a result, Type II fibers may take on characteristics similar to Type I fibers, enhancing endurance and resilience under altered functional demands.

Answer 10

Weak electric current flows through body Voltage is measured to calculate resistance and reactance of body BIA measures total body water from which lean body mass is calculated using assumption all tissues have same degree of hydration

Answer 11

Uses low dose X-ray Analyses distribution of fat, muscle mass and bone in the body

Answer 12

Specialized X-ray equipment to produce cross-sectional images of the body

Answer 13

No exposure to radiation Images the soft-tissue structures of the body = muscle, bones and joints Often clearer and more detailed than with other imaging methods

Answer 14

Magnetic field strength of main magnet is much lower than MRI Generates information based on radiation frequencies

Answer 15

Measuring muscle strength is the easiest quantifiable way to measure muscle health Measure knee extensor strength Muscle quantity does not reflect its QUALITY

Answer 16

Reduced satellite cell pool Fibre loss = rare because so many nuclei Fibre atrophy = common due to other factors, protein aggregates and mitochondrial damage Intramuscular fat Fibrosis Denervation Capillary attrition

Answer 17

Muscle fiber loss involves a reduction in the total number of muscle fibers. This can occur due to various factors, such as aging, injury, or certain diseases. Conditions like muscular dystrophy or prolonged immobilization can lead to the death of muscle fibers, resulting in fewer fibers overall. Muscle fiber atrophy, on the other hand, refers to a decrease in the size of existing muscle fibers rather than a reduction in their number. This can occur due to disuse (like sedentary lifestyles), aging, or hormonal changes. Atrophy can be reversible with proper exercise and nutrition. Muscle fiber atrophy is generally more common, especially in older adults or those who are less active. While muscle fiber loss can occur, it typically happens under specific pathological conditions or prolonged disuse. In many cases, muscle atrophy can be addressed through targeted exercise and nutrition, while fiber loss may require more complex interventions.

Answer 18

Look at the shape, are they a regular honeycomb shape? Cannot look at number of myofibres because people have different densities of muscle fibres depending on their size

Answer 19

Because it disrupts their connection and communication Shown in diabetic and obese patients

Answer 20

As we age Type 1 fibres become more clustered We lost Type 2 fibres much more than Type 1 So Type 1 fibre increases to compensate for that Type 2 atrophies and Type 1 hypertrophies

Answer 21

Missense = a single nucleotide change results in the substitution of one amino acid for another in a protein sequence Nonsense = a single nucleotide change converts a codon that originally codes for an amino acid into a stop codon. This premature stop codon leads to the truncation of the protein during translation, resulting in a shorter, often nonfunctional protein

Answer 22

Myostatin sequence contains a missense mutation in exon 3 Results in substitution of Tyr for invariant Cys in mature region of protein

Answer 23

Myostatin is a protein that normally inhibits muscle growth. When it is mutated, its function is disrupted, leading to increased muscle mass and reduced fat deposition This mutation results in a condition known as double muscling, where the animals exhibit larger, more developed muscles compared to typical cattle. The enhanced muscle growth makes Piedmontese cattle particularly valued for their lean meat, as they produce more muscle tissue with less fat.

Answer 24

Gross muscle hypertrophy in children = associated with myostatin mutation Absence of mature myostatin means that there is less inhibition of muscle growth

Answer 25

Myostatin negatively regulates muscle growth by inhibiting the mTOR, which is crucial for protein synthesis and muscle hypertrophy

Answer 26

Because factors were not controlled And trials in mice were not acurrately reflectd in humans

Skeletal Muscle Ageing LT4 Flashcards

(51 cards)