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Kin 267 (Phys. 1) > muscle (Pt. 2) > Flashcards

muscle (Pt. 2) Flashcards

1
Q

Q: What is the “marbling effect” in aging muscle?

A

A: The gradual infiltration of fat into muscle tissue, similar to marbling seen in meat, where fat appears between and within muscle fibers.

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2
Q

Q: What are the causes of the marbling effect in aging muscle?

A

A: Natural aging process, decreased physical activity, hormonal changes, and reduced muscle protein synthesis.

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3
Q

Q: How does the marbling effect impact muscle quality and function?

A

A: It reduces muscle quality, decreases muscle strength, impacts muscle function, and increases the risk of mobility issues.

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4
Q

Q: What are some prevention and management strategies for the marbling effect?

A

A: Regular exercise (especially strength training), proper nutrition, adequate protein intake, and maintaining physical activity levels.

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5
Q

Q: How is the marbling effect related to sarcopenia?

A

A: It is part of sarcopenia (age-related muscle loss) and can be partially prevented or slowed through lifestyle interventions.

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6
Q

Q: What nutritional factor is important for preventing the marbling effect?

Q: What type of exercise is particularly beneficial for managing the marbling effect?

A

A: Adequate protein intake.
A: Strength training.

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7
Q

Q: How does muscle mass differ between young and old muscle?

A

A: Young muscle has higher mass and density for greater strength, while old muscle shows loss of mass (sarcopenia) and decreased strength.

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8
Q

Q: What is the difference in fat content between young and old muscle?

A

A: Young muscle has lower intramuscular fat levels, while old muscle shows increased fat infiltration (marbling effect).

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9
Q

Q: How does fiber composition differ between young and old muscle?

A

A: Young muscle has a balanced mix of fast and slow-twitch fibers, while old muscle shows decreased fast-twitch fibers.

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10
Q

Q: What is the difference in regenerative capacity?
(young vs. old muscle)

A

A: Young muscle has greater ability to recover and regenerate, while old muscle has reduced regenerative capacity due to fewer satellite cells.

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11
Q

Q: How does functional performance compare?
(young VS. Old muscle)

A

A: Young muscle performs better in strength and endurance activities, while old muscle may struggle with daily activities.

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12
Q

Q: What impacts quick, explosive movements in older muscle?

A

A: The decrease in fast-twitch fibers.

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13
Q

Q: Why is recovery slower in older muscle?

A

A: Due to reduced regenerative capacity and fewer satellite cells.

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14
Q

Q: What is sarcopenia?

A

A: Sarcopenia is the age-related loss of muscle mass and strength.

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15
Q

Q: What role does oxidative stress play in sarcopenia?

A

A: Oxidative stress damages cellular structures, contributing to muscle deterioration.

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16
Q

Q: How do hormonal changes affect sarcopenia?

A

A: Alterations in hormones and growth factors impact muscle growth and repair.

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17
Q

Q: What is the effect of satellite cell dysfunction in sarcopenia?

A

A: Impaired satellite cells reduce muscle repair and regeneration capacity.

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18
Q

Q: How do neural changes contribute to sarcopenia?

A

A: Loss of motor neurons and changes in neural plaques weaken muscle function.

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19
Q

Q: What is the role of mitochondrial dysfunction in sarcopenia?

A

A: Reduced energy production in muscle cells affects overall muscle health.

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20
Q

Q: What impact does inactivity have on sarcopenia?

A

A: Inactivity leads to muscle degradation and accelerates sarcopenia.

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21
Q

Q: How does an imbalance in protein metabolism contribute to sarcopenia?

A

A: Disruption in protein synthesis and breakdown reduces muscle quality and function.

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22
Q

Q: What is the effect of chronic inflammation on muscle tissue in sarcopenia?

A

A: Chronic inflammation negatively affects muscle health and accelerates muscle loss.

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23
Q

Q: How does apoptosis influence sarcopenia?

A

A: Increased cell death leads to loss of muscle fibers over time.

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24
Q

Q: What are microvascular changes in sarcopenia?

A

A: Reduced blood supply adversely impacts muscle health and regeneration.

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25
Q

Q: What fiber types are present in young, healthy muscles?

A

A: Type I (Slow Oxidative) and Type IIa (Fast Oxidative-Glycolytic)

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26
Q

Q: What are the main factors that cause muscle fiber transitions?

A

A: Aging, inactivity, disease, exercise/training, and hormonal changes

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27
Q

Q: What fiber transition occurs with aging and inactivity?

A

A: Type IIa fibers transition to Type I fibers, with loss of fast-twitch fibers

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28
Q

Q: What is the functional impact of age-related fiber transitions?

A

A: Decrease in power and strength due to loss of fast-twitch fibers

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29
Q

Q: How does training affect muscle fiber types?

A

A: Can maintain Type IIa fibers, improve fiber characteristics, and shift fiber properties based on training type

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30
Q

Q: Can training prevent age-related fiber transitions?

A

A: Yes, training can help maintain Type IIa fibers and their characteristics

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31
Q

Q: How can fiber properties be modified?

A

A: Through specific types of training and exercise

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32
Q

Q: What are the main changes in fiber types with aging?

A

A: Decrease in Type IIa (fast-twitch) fibers, increase in Type I (slow-twitch) fibers, and loss of total fiber number

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33
Q

Q: What are the five main performance impacts of age-related fiber changes?

A

A: 1. Reduced power output 2. Decreased strength 3. Slower movement speed 4. Better endurance capacity 5. Lower explosive force

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34
Q

Q: How does endurance capacity change with aging?

A

A: It may improve due to increased proportion of Type I (slow-twitch) fibers

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35
Q

Q: Why does explosive force decrease with age?

A

A: Due to loss of Type IIa (fast-twitch) fibers and reduced total fiber number

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36
Q

Q: What type of training is most important for maintaining Type IIa fibers?

A

A: Resistance training and high-intensity exercise

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37
Q

Q: What role do motor units play in age-related muscle changes?

A

A: Their loss contributes to decreased muscle function and fiber type changes

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38
Q

Q: What type of muscle fibers do fast-twitch motor neurons connect to?

A

A: Fast-twitch (FT) muscle fibers

39
Q

Q: What are fast-twitch fibers responsible for?

A

A: Quick, powerful movements

40
Q

Q: What type of muscle fibers do slow-twitch motor neurons connect to?

A

A: Slow-twitch (ST) muscle fibers

41
Q

Q: What are slow-twitch fibers designed for?

A

A: Endurance and sustained activities

42
Q

Q: What is the relationship between motor neurons and muscle fiber types?

A

A: Fast-twitch neurons connect to fast-twitch fibers, and slow-twitch neurons connect to slow-twitch fibers

43
Q

Q: How do motor neurons determine muscle fiber function?

A

A: The type of motor neuron (fast or slow) determines whether the muscle fiber will be used for quick movements or endurance activities

44
Q

Q: What is the main functional difference between fast and slow-twitch fibers?

A

A: Fast-twitch fibers provide power and speed, while slow-twitch fibers provide endurance

45
Q

Q: What happens when a fast-twitch motor neuron is lost?

A

A: Loss of nerve connection to fast-twitch muscle fibers, leading to denervation

46
Q

Q: What happens to slow-twitch motor neurons during this process?

A

A: They remain functional and maintain connections with slow-twitch fibers; may reinnervate some former fast-twitch fibers

47
Q

Q: What are the immediate effects of fast-twitch fiber denervation?

A

A: Muscle fibers lose nerve supply, leading to reduced strength and power, and increased reliance on slow-twitch fibers

48
Q

Q: What happens to a denervated muscle fiber?

A

A: It becomes “orphaned,” begins to atrophy, loses strength and function, and may die if not reinnervated

49
Q

Q: What are the possible outcomes for denervated fast-twitch fibers?

A

A: They may die completely, get “adopted” by slow-twitch motor neurons, or change characteristics to match new nerve type

50
Q

Q: How does reinnervation by slow-twitch neurons affect muscle fibers?

A

A: Fibers become more slow-twitch in nature, changing their characteristics

51
Q

Q: What are the functional impacts of fast-twitch denervation?

A

A: Reduced power output, decreased strength, slower contractions, and changed muscle characteristics

52
Q

Q: What is the overall effect on muscle performance?

A

A: Decrease in power and speed capabilities, with greater reliance on slow-twitch characteristics

53
Q

Q: What is the key difference between initial denervation and complete denervation?

A

A: Initial denervation shows loss of nerve supply while fibers remain organized; complete denervation shows disorganized and degrading muscle fibers

54
Q

Q: What happens to muscle fibers immediately after losing nerve supply?

A

A: They remain present and organized initially, but begin losing function

55
Q

Q: What happens to muscle fibers over time without nerve input?

A

A: They become disorganized, begin to degrade, and may eventually die off completely

56
Q

Q: What can prevent complete muscle fiber death after denervation?

A

A: Reinnervation by other motor neurons (typically slow-twitch)

57
Q

Q: How does muscle fiber structure change during denervation?

A

A: It progresses from organized to disorganized, with eventual deterioration of fiber structure

58
Q

Q: What is the final outcome if denervated muscle fibers are not reinnervated?

A

A: Complete degradation and death of the muscle fibers

59
Q

Q: Why is nerve input essential for muscle fiber survival?

A

A: Without nerve input, muscle fibers cannot maintain their structure and function, leading to deterioration

60
Q

Q: What is the progression of denervation effects?

A

A: Loss of nerve supply → loss of organization → degradation of structure → potential fiber death

61
Q

Q: What is reinnervation in muscle fibers?

A

A: The process where slow-twitch motor neurons extend new connections to denervated muscle fibers

62
Q

Q: What happens to reinnervated fibers over time?

A

A: They may transition to behave more like slow-twitch fibers

63
Q

Q: What is the neuromuscular junction (NMJ)?

A

A: The structure where motor neurons connect and communicate with muscle fibers to enable contraction

64
Q

Q: How do slow-twitch motor neurons compensate for motor neuron loss?

A

A: They extend new connections to innervate denervated muscle fibers

65
Q

Q: What is the functional significance of reinnervation by slow-twitch neurons?

A

A: It preserves muscle fiber function but changes the fiber characteristics to slow-twitch properties

66
Q

Q: What structure must be rebuilt during reinnervation?

A

A: The neuromuscular junction (NMJ)

67
Q

Q: What is the primary purpose of the NMJ?

A

A: To enable communication between motor neurons and muscle fibers for muscle contraction

68
Q

Q: What is the main functional change after fiber type conversion?

A

A: Increased endurance capacity but reduced power and speed

69
Q

Q: What does a mix of fiber types indicate about muscle function?

A

A: It suggests varied functional capabilities, balancing endurance and strength/power

70
Q

Q: Why is fiber type diversity important in muscle tissue?

A

A: It allows muscles to perform both endurance and power-based activities effectively

71
Q

Q: What functional advantage does having mixed fiber types provide?

A

A: It enables muscles to handle both sustained low-intensity and brief high-intensity activities

72
Q

Q: What are the possible causes of increased slow-twitch fiber proportion?

A

A: Aging, inactivity leading to fiber type conversion, or adaptation to endurance-focused activities

73
Q

Q: What types of activities might cause adaptation?

A

A: Endurance-focused activities or exercises, or lack of high-intensity activities

74
Q

Q: What does this fiber type distribution suggest about muscle function?

A

A: The muscle is better suited for endurance activities than power activities

75
Q

Q: What are the primary contributors to skeletal muscle atrophy?

A

A: Inactivity, aging, inflammation, insulin resistance, critical illness, and anabolic resistance

76
Q

Q: How do inactivity and aging contribute to muscle atrophy?

A

A: They affect microvasculature, reduce satellite cell function, increase inflammation, and lead to anabolic resistance, reducing muscle regeneration

77
Q

Q: What is anabolic resistance?

A

A: A reduced responsiveness of muscle tissue to anabolic stimuli like protein and exercise, making it harder to build and maintain muscle mass

78
Q

Q: How does insulin resistance contribute to muscle atrophy?

A

A: It impairs cell glucose/nutrient uptake, reducing muscle building and increasing muscle breakdown

79
Q

Q: What is the role of myoblasts in muscle health?

A

A: Myoblasts help repair muscles, but their activity is reduced due to satellite cell decline with aging

80
Q

Q: Name three lifestyle interventions to prevent age-related muscle loss.

A

A:

Resistance training
High-protein diet
Load-bearing cardio (e.g., running, walking, and hiking)

81
Q

Q: Why is building muscle during youth important?

A

A: It creates a “muscle bank,” maximizing muscle mass to mitigate the impact of natural muscle loss with aging

82
Q

Q: What role does inflammation play in muscle atrophy?

A

A: Chronic inflammation increases anabolic resistance, reducing the ability to build and maintain muscle

83
Q

Q: What critical life changes can decrease physical activity between ages 30-60?

A

A: Work/job demands, raising children, financial constraints, and retirement

84
Q

Q: What is the relationship between physical activity and anabolic resistance?

A

A: Regular activity, especially resistance training, reduces anabolic resistance and promotes muscle health

85
Q

Q: What is the current government recommended dietary allowance (RDA) for protein?

A

A: 0.8 grams per kg of body weight per day

86
Q

Q: Why is the current RDA for protein considered inadequate?

A

A: Research shows protein intakes less than 1.0g per kg leads to rapid muscle loss and dysfunction; 0.8g/day only maintains nitrogen balance

87
Q

Q: What is nitrogen balance?

A

A: The state where protein intake supports tissue growth and repair without having too much or too little nitrogen in your system

88
Q

Q: Why is 0.8g/kg protein insufficient for muscle health?

A

A: It’s only the bare minimum to maintain nitrogen balance, not enough to build or maintain optimal muscle mass

89
Q

Q: What’s problematic about the current protein RDA for older adults?

A

A: It doesn’t account for increased protein needs during aging to prevent muscle loss

90
Q

Q: Why do older adults need more protein than the RDA suggests?

A

A: To prevent rapid muscle loss and maintain proper muscle function during aging

91
Q

How much protein should you ingest per day?

A

1.6-2.2 grams/kg

92
Q

How much protein should you ingest per meal if < 40 years of age?

A

0.25 grams/kg

93
Q

How much protein should you ingest per meal if > 40 years of age?

A

0.40 grams/kg

94
Q

When is the best time to consume protein for muscle growth and recovery?

A

Doesn’t matter

Kin 267 (Phys. 1) (17 decks)

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