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

muscle (Pt. 1) Flashcards

1
Q

what are three type of muscular tissue?

A

skeletal, cardiac and smooth muscle

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2
Q

Q: What are the main characteristics of skeletal muscle?

A

A: Moves bones, has striations, consciously controlled with some subconscious functions, connected to somatic nervous system

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3
Q

Q: Where is cardiac muscle found and what controls it?

A

A: Found only in heart, controlled by hormones and neurotransmitters, part of autonomic nervous system

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4
Q

What is unique about cardiac muscle’s function?

A

A: Has natural pacemaker (autorhythmicity) and cannot be consciously controlled

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5
Q

Q: Where is smooth muscle located?

A

A: Found in hollow internal structures, blood vessels, airways, organs, and skin (hair follicles)

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6
Q

Q: What are the visual characteristics of smooth muscle?

A

A: No striations, appears smooth

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7
Q

Q: How is smooth muscle controlled?

A

A: Controlled by autonomic nervous system and hormones, some have autorhythmicity

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8
Q

Q: What type of muscle has striations?

A

A: Both skeletal and cardiac muscle have striations

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9
Q

Q: Which muscles are involuntary?

A

A: Cardiac and smooth muscle are involuntary

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10
Q

Which muscle type is voluntary?

A

A: Skeletal muscle is voluntary (with some subconscious control)

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11
Q

Functions of Muscular Tissue

A

Producing body movements
Stabilizing body positions
Storing and mobilizing substances within the body
Generating heat

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12
Q

Q: What is the role of muscles in producing body movements?

A

A: Controls whole body movements (like walking and running) and localized movements (like grasping and typing), working with bones and joints.

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13
Q

Q: How do muscles stabilize body positions?

A

A: Maintains posture and joint stability, enabling standing and sitting (e.g., neck muscles keeping the head upright).

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14
Q

Q: How do muscles aid in moving substances in the body?

A

A: The heart pumps blood, blood vessels regulate flow, and muscles in the digestive, reproductive, and urinary systems move substances.

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15
Q

Q: What role do skeletal muscles play in fluid movement?

A

A: They aid in lymph and venous flow in the body.

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16
Q

Q: How do muscles contribute to generating heat?

A

A: Produce heat during contraction, helping to maintain body temperature.

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17
Q

Q: What is shivering related to muscle function?

A

A: Involuntary contractions of muscles that increase heat production.

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18
Q

Q: What are the basic states of skeletal muscle activity?

A

A: Two primary states: contraction and relaxation, working via antagonistic pairs

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19
Q

Q: What percentage of total body mass is skeletal muscle in average adults?

A

A: 40-50% of total body mass

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20
Q

Q: What factors affect skeletal muscle percentage in the body?

A

A: Age, sex, fitness level, and overall health status

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21
Q

Q: What are the main effects of exercise on skeletal muscle?

A

A: Increased muscle mass (hypertrophy), enhanced strength, improved endurance, better neural recruitment, and increased metabolic efficiency

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22
Q

Q: How is skeletal muscle’s functional capacity measured?

A

A: Through muscle strength, power output, endurance, and recovery rate

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23
Q

Q: What is the primary energy conversion function of skeletal muscle?

A

A: Converting chemical energy to mechanical energy

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24
Q

Q: What factors influence skeletal muscle efficiency?

A

A: Training status, muscle fiber type, metabolic health, neuromuscular coordination, and energy system utilization

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25
Q

Q: What is the clinical significance of skeletal muscle?

A

A: Important for physical performance, metabolic health, daily function, quality of life, and disease prevention

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26
Q

Q: What is a skeletal muscle composed of?

A

A: Hundreds to thousands of elongated cells called muscle fibers (myocytes), along with connective tissues, blood vessels, and nerves

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27
Q

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

A

A: They are early muscle cells that combine/merge to form muscle fibers

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28
Q

Q: What are satellite cells and their function?

A

A: Special cells that act as muscle stem cells, helping with muscle growth, repair, regeneration, and maintenance

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29
Q

Q: What is a myonuclear domain?

A

A: A specific area of the muscle fiber controlled by each nucleus, critical for cell function and maintenance

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30
Q

Q: What characterizes mature muscle fiber structure?

A

A: They are multinucleated cells with multiple myonuclear domains that control specific areas

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31
Q

Q: How do satellite cells change with age?

A

A: They are abundant during embryonic development but gradually decrease with age, leading to reduced regenerative and repair capacity

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32
Q

Q: What are the consequences of aging on muscle tissue?

A

A: Progressive decrease in muscle mass (sarcopenia), reduced repair capacity, increased fibrosis, decreased strength and power output

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33
Q

Q: What clinical implications result from age-related muscle changes?

A

A: Impacts physical independence, fall risk, overall mobility, quality of life, and metabolic health

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34
Q

Q: What are the main strategies for preventing age-related muscle decline?

A

A: Exercise, proper nutrition, hormone balance, and lifestyle modifications

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35
Q

Q: What is the outermost protective layer of a whole muscle?

A

A: The epimysium

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36
Q

Q: What are fascicles and what surrounds them?

A

A: Bundles within the muscle, surrounded by perimysium

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37
Q

Q: What two layers protect individual muscle fibers?

A

A: Endomysium and sarcolemma (cell membrane)

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38
Q

Q: What are myofibrils?

A

A: Thread-like structures inside muscle fibers responsible for contraction

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39
Q

Q: What is the basic functional unit of muscle cells?

A

A: The sarcomere

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40
Q

Q: What are the two main types of myofilaments in muscle tissue?

A

A: Thick filaments (myosin) and thin filaments (actin)

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41
Q

Q: What is the role of troponin?

A

A: A regulatory protein that binds to calcium and helps control muscle contraction

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42
Q

Q: How are muscles connected to bones?

A

A: Through tendons

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43
Q

Q: What is the hierarchical organization of muscle tissue (from largest to smallest)?

A

A: Whole muscle → Fascicles → Muscle Fibers → Myofibrils → Myofilaments

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44
Q

Q: What are the main components at the skeletal muscle level?

A

A: Muscle fascicles, muscle fibers, blood vessels, and nerves, all enclosed by epimysium

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45
Q

Q: What is a muscle fascicle and what surrounds it?

A

A: A bundle of muscle fibers surrounded by perimysium

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46
Q

Q: What are the key components of a muscle fiber?

A

A: Sarcoplasmic reticulum, sarcolemma, myofibrils, sarcoplasm, multiple nuclei, T tubules, terminal cisterns, and mitochondria

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47
Q

Q: What is the role of the sarcoplasmic reticulum?

A

A: Stores calcium, which is crucial for muscle contraction

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48
Q

Q: What are T tubules and terminal cisterns responsible for?

A

A: T tubules transmit electrical signals into the muscle fiber, and terminal cisterns work with T tubules to release calcium

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49
Q

Q: What is a myofibril and what are its main components?

A

A: Contractile elements within sarcoplasm containing sarcomeres, Z discs, thick filaments (myosin), and thin filaments (actin)

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50
Q

Q: What is a sarcomere?

A

A: The basic functional unit of a myofibril, defined by Z discs

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51
Q

Q: Where are the nuclei located in a muscle fiber?

A

A: Multiple nuclei are located on the periphery of the muscle fiber

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52
Q

Sarcomere

A

Basic functional unit of a myofibril.

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53
Q

Z Disc

A

Defines the boundaries of each sarcomere.

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54
Q

Q: What are the two types of myofilaments?

A

A: Thick filaments (composed of myosin) and thin filaments (composed of actin, tropomyosin, and troponin)

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55
Q

Q: What defines the boundaries of each sarcomere?

A

A: Z discs

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56
Q

Q: How are thick and thin filaments arranged in a sarcomere?

A

A: Thick and thin filaments are arranged between the Z discs

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57
Q

Q: What mechanism allows for muscle shortening during contraction?

A

A: Thin filaments slide past thick filaments, known as the sliding filament mechanism

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58
Q

Q: What is the structure of thick filaments?

A

A: Composed of myosin with two intertwined tails known as the myosin heavy chain (types one and two)

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59
Q

Q: What is the role of thin filaments in muscle contraction?

A

A: Muscle contraction occurs through the sliding of thin filaments (actin) over thick filaments (myosin)

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60
Q

What are the two main components involved in muscle contraction at the filament level?

A

A: Myosin (thick filaments) and actin (thin filaments)

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61
Q

Q: How does muscle contraction occur at the sarcomere level?

A

A: Myosin and actin filaments slide past each other, causing the sarcomere to shorten

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62
Q

Q: What is the hierarchical structure of muscle from largest to smallest component?

A

A: Muscle → Muscle Fascicles → Muscle Fibers → Myofibrils → Sarcomeres → Filaments

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63
Q

Q: What surrounds muscle fascicles to support their function?

A

A: Arteries, veins, and nerves for blood supply and control

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64
Q

Q: What defines the boundaries of a sarcomere?

A

A: Z lines mark the boundaries, with M lines in the center

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65
Q

Q: What is the relationship between myofibrils and sarcomeres?

A

A: Myofibrils are composed of repeating units called sarcomeres, which are the functional units of contraction

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66
Q

Q: How does muscle movement ultimately occur?

A

A: Myofibrils shorten during contraction through the sliding of filaments, leading to muscle movement

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67
Q

Q: What is a sarcomere and what defines its boundaries?

A

A: The basic contractile unit of muscle, extending from one Z disc to the next

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68
Q

Q: What is the function of Z discs?

A

A: Mark the boundaries of sarcomeres and anchor thin filaments (actin)

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69
Q

Q: What is the I band and where is it located?

A

A: Contains only thin filaments and is located adjacent to the Z disc

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70
Q

Q: What is the A band?

A

A: Spans the length of thick filaments and includes areas where thin and thick filaments overlap

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71
Q

Q: What is the H band and where is it found?

A

A: The central region within the A band that contains only thick filaments (myosin) when the muscle is at rest

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72
Q

Q: What is the M line and its function?

A

A: Located at the center of the H band, serves as an anchor point for thick filaments

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73
Q

Q: How does the sliding mechanism work in muscle contraction?

A

A: Myosin pulls on actin, drawing the Z discs closer together, causing contraction

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74
Q

Q: What are zones of overlap?

A

A: Areas where thick and thin filaments overlap, critical for muscle contraction

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75
Q

Q: What occurs during muscle contraction in the sliding filament mechanism?

A

A: Myosin heads attach to thin filaments and “walk” toward the M line, pulling thin filaments inward.

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76
Q

Q: How do the sarcomeres change during contraction?

A

A: Thin filaments slide toward the center, causing the I band and H zone to narrow or disappear.

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77
Q

Q: What happens to the A band during muscle contraction?

A

A: The width of the A band remains the same, while the lengths of thick and thin filaments do not change.

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78
Q

Q: How do Z discs move during contraction?

A

A: As thin filaments slide inward, the Z discs move closer together, shortening the sarcomere.

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79
Q

Q: What is the overall effect of the sliding filament mechanism on muscle fibers?

A

A: The shortening of sarcomeres leads to the shortening of the muscle fiber and the entire muscle.

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80
Q

Q: What is the correct order of muscle components from largest to smallest?

A

A: 1. Whole muscle 2. Muscle fascicles 3. Muscle fibers 4. Myofibrils 5. Sarcomeres 6. Actin and myosin 7. Myosin heavy chains

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81
Q

Q: What type of tissue surrounds muscle fascicles?

A

A: Perimysium

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82
Q

Q: What is the smallest functional unit of muscle tissue?

A

A: The sarcomere

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83
Q

Q: What are the two protective layers of muscle fibers?

A

A: Endomysium and sarcolemma

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84
Q

Q: What wraps the whole muscle?

A

A: Epimysium

85
Q

Q: What are myofibrils composed of?

A

A: Repeated units called sarcomeres

86
Q

Q: What is the relationship between actin and myosin?

A

A: Actin (thin filament) interacts with myosin (thick filament) to facilitate contraction

87
Q

Q: Which proteins are considered “contractile proteins”?

A

A: Actin and myosin are the contractile proteins

88
Q

Q: Which proteins are considered “regulatory proteins”?

A

A: Troponin and tropomyosin are the regulatory proteins

89
Q

Q: Which protein binds to calcium?

A

A: Troponin binds to calcium

90
Q

Q: What structure is bordered by Z-discs?

A

A: The sarcomere is bordered by Z-discs

91
Q

Q: Which protein blocks binding sites on actin?

A

A: Tropomyosin blocks binding sites on actin

92
Q

Q: Which protein controls the speed of contraction?

A

A: Myosin heavy chains control the speed of contraction

93
Q

Q: What encloses a muscle fiber?

A

A: The sarcolemma (cell membrane)

94
Q

Q: What is the role of calcium ions in muscle contraction?

A

A: Released from sarcoplasmic reticulum, binds to troponin, causing tropomyosin to move and expose binding sites on actin

95
Q

Q: What are T tubules and their function?

A

A: Indentations of the sarcolemma that facilitate rapid transmission of contraction signals throughout the muscle fiber

96
Q

Q: What is the function of myoglobin?

A

A: Binds to oxygen, providing an oxygen reserve for muscle metabolism

97
Q

Q: What is the purpose of glycogen granules in muscle fibers?

A

A: Serve as an energy reserve, utilized during muscle contraction

98
Q

Q: What are the main energy-producing structures in muscle fibers?

A

A: Mitochondria, which provide ATP for muscle contractions

99
Q

Q: What are the main structural components of muscle fibers?

A

A: Myofibrils containing sarcomeres (made of thick and thin filaments) and Z discs

100
Q

Q: What initiates muscle contraction?

A

A: Calcium ions are released into the muscle cell, bind to troponin, which moves tropomyosin to expose binding sites on actin

101
Q

Q: What happens in the first step of the contraction cycle?

A

A: Myosin head breaks down ATP, stores energy and gets into a “cocked” position

102
Q

Q: What occurs during the connection step?

A

A: The energized myosin head attaches to actin, forming a “cross-bridge”

103
Q

Q: What happens during the power stroke?

A

A: Myosin head pivots from 90° to 45°, pulls the thin filament creating muscle force, and releases ADP

104
Q

Q: How does the contraction cycle end?

A

A: A new ATP molecule binds, causing the myosin head to release from actin

105
Q

Q: What is a cross-bridge?

A

A: The connection formed when an energized myosin head attaches to actin

106
Q

Q: Is the contraction cycle a one-time event?

A

A: No, this process repeats many times during muscle contraction

107
Q

Q: What are the characteristics of slow oxidative fibers?

A

A: They are darker due to higher myoglobin and mitochondria content, used for endurance, and can work for long periods without fatigue.

108
Q

Q: How do fast glycolytic fibers differ from slow oxidative fibers?

A

A: Fast glycolytic fibers are lighter and larger, contain less myoglobin, and produce quick bursts of energy but tire quickly.

109
Q

Q: What defines fast oxidative-glycolytic fibers?

A

A: They have properties between slow oxidative and fast glycolytic fibers, suitable for activities that require both speed and endurance.

110
Q

Q: What is the role of myoglobin in muscle fibers?

A

A: Myoglobin stores and carries oxygen within muscle cells, facilitating energy production during exercise.

111
Q

Q: What is the general percentage distribution of muscle fibers in humans?

A

A: Approximately 50% slow oxidative (SO) and 50% fast fibers.

112
Q

Q: What are the three types of muscle fibers?

A

A: Slow oxidative (SO), fast oxidative-glycolytic (FOG), and fast glycolytic (FG) fibers.

113
Q

Q: What is a characteristic of slow oxidative (SO) fibers?

A

A: They are good for endurance and use oxygen efficiently; they appear dark red due to high myoglobin.

114
Q

Q: What is the main energy source for slow oxidative fibers?

A

A: Aerobic (using oxygen).

115
Q

Q: What activities are slow oxidative fibers ideal for?

A

A: Marathon running and maintaining posture; they are highly resistant to fatigue.

116
Q

Q: What defines fast oxidative-glycolytic (FOG) fibers?

A

A: They are a mix of speed and endurance, large, dark red, and contract quickly with moderate fatigue resistance.

117
Q

Q: What is the main energy source for fast oxidative-glycolytic fibers?

A

A: They can use both aerobic and anaerobic systems.

118
Q

Q: What activities are fast oxidative-glycolytic fibers good for?

A

A: Activities like walking and sprinting.

119
Q

Q: What are the characteristics of fast glycolytic (FG) fibers?

A

A: Focused on quick bursts of energy, appear white, and tire quickly.

120
Q

Q: What is the main energy source for fast glycolytic fibers?

A

A: Anaerobic (without oxygen).

121
Q

Q: Where are slow oxidative fibers primarily found?

A

A: In muscles used constantly, like those in the neck, back, and legs.

122
Q

Q: Which muscles primarily contain fast glycolytic (FG) fibers?

A

A: Muscles in the shoulders and arms, used for quick, strong actions like lifting and throwing.

123
Q

Q: Where are fast oxidative-glycolytic (FOG) fibers found?

A

A: In leg muscles, which need both endurance and strength.

124
Q

Q: How are motor units activated based on task demands?

A

A: SO fibers for light tasks, FOG fibers for more force, and FG fibers for maximum effort.

125
Q

Q: Who controls the activation of muscle fibers during tasks?

A

A: The brain and spinal cord.

126
Q

Q: What is a key characteristic of slow oxidative (SO) fibers?

A

A: High myoglobin content, appears dark red, with many capillaries and mitochondria, and has a smaller diameter.

127
Q

Q: What defines fast oxidative-glycolytic (FOG) fibers?

A

A: High myoglobin content (dark red), many capillaries and mitochondria, and an intermediate diameter.

128
Q

Q: What are the characteristics of fast glycolytic (FG) fibers?

A

A: Low myoglobin content (white), fewer capillaries, few mitochondria, and a larger diameter.

129
Q

Q: What determines the mix of muscle fiber types in an individual?

A

A: It is mostly determined by genetics.

130
Q

Q: How does the diameter of slow oxidative (SO) fibers compare to fast glycolytic (FG) fibers?

A

A: SO fibers have a smaller diameter compared to larger FG fibers.

131
Q

Q: What benefit do the high capillarity and mitochondrial content in SO and FOG fibers provide?

A

A: They enhance endurance by improving oxygen delivery and energy production.

132
Q

Q: What are the three main energy systems in muscle fibers?

A

A: 1. Immediate system (ATP-phosphocreatine) 2. Short-term anaerobic system (glycolysis) 3. Long-term aerobic system (oxygen-dependent)

133
Q

Q: How long does the immediate energy system last?

A

A: Seconds (uses stored ATP and phosphocreatine)

134
Q

Q: How long can the short-term anaerobic system sustain activity?

A

A: Up to a few minutes

135
Q

Q: Which energy system is used for extended activities?

A

A: The long-term aerobic system, which uses oxygen to break down glucose

136
Q

Q: Why do we continue breathing heavily after exercise?

A

A: To provide extra oxygen needed to convert lactic acid back to energy and restore ATP levels

137
Q

Q: What is Creatine Kinase (CK) and its primary role?

A

A: An enzyme that converts creatine and ATP into phosphocreatine and ADP, helping store and release energy quickly for intense activities.

138
Q

Q: Which muscle fiber type has the highest amount of CK?

A

A: Fast Glycolytic (FG) Fibers

139
Q

Q: Which fiber type has the medium amount of CK?

A

A: Fast Oxidative-Glycolytic (FOG) Fibers

140
Q

Q: Which fiber type has the lowest amount of CK?

A

A: Slow Oxidative (SO) Fibers

141
Q

Q: How does glycogen storage compare between fiber types?

A

A: FG fibers have large stores for quick power (like a sports car), SO fibers have less but use it more efficiently (like a hybrid car)

142
Q

Q: What happens to excess glucose in the body?

A

A: It’s converted into glycogen and stored in muscle cells and the liver

143
Q

Q: What is the order of muscle fiber recruitment during activity?

A

A: 1. SO fibers (low intensity) 2. FOG fibers (moderate intensity) 3. FG fibers (maximum effort)

144
Q

Q: What was the traditional view of muscle fiber types?

A

A: Muscle fibers were thought to be strictly one type (either Type I/SO, Type IIa/FOG, or Type IIb/FG)

145
Q

Q: What are hybrid fibers?

A

A: Single muscle fibers that can contain characteristics of multiple fiber types

146
Q

Q: What unique characteristic can hybrid fibers display?

A

A: Different segments of the same fiber can show properties of both Type I and Type II fibers

147
Q

Q: What factors can cause muscle fibers to change their properties?

A

A: Training type, activity level, and environmental demands

148
Q

Q: How has our understanding of muscle fiber adaptability changed?

A

A: We now know muscles are more adaptable than previously thought, with fibers able to change their characteristics

149
Q

Q: Why is the discovery of hybrid fibers significant for athletes?

A

A: It helps explain why athletes can excel at both power and endurance activities

150
Q

Q: How many muscle fiber types do healthy, active humans typically have?

A

A: Only two main types: Type I (Slow Oxidative) and Type IIa (Fast Oxidative-Glycolytic)

151
Q

Q: Under what conditions do Type IIx/IIb fibers appear?

A

A: During prolonged periods of inactivity, spaceflight, and spinal cord injury

152
Q

Q: What is the relationship between Type IIx and Type IIa fibers?

A

A: Type IIx are essentially a “downgraded” version of Type IIa fibers

153
Q

Q: What muscle fiber types do cheetahs possess?

A

A: All types: Type I, IIa, IIx, and IIb

154
Q

Q: Why do cheetahs need all muscle fiber types?

A

A: For a combination of speed, power, and endurance necessary for survival and hunting

155
Q

Q: Do active humans have the Type IIx gene?

A

A: Yes, but it isn’t actively expressed

156
Q

Q: What are the two main proteins found in a sarcomere?

A

A: Actin and Myosin

157
Q

Q: Which proteins are primarily involved in muscle contraction?

A

A: Actin and Myosin

158
Q

Q: What proteins can prevent muscle contraction?

A

A: Tropomyosin and Troponin

159
Q

Q: What is the slowest contracting fiber type?

A

A: Type I fiber

160
Q

Q: What is the energy currency of a cell?

A

A: ATP

161
Q

Q: Which enzyme is involved in muscle contraction?

A

A: ATPase

162
Q

Q: What is muscular hypertrophy?

A

A: Enlargement of existing muscle fibers due to increased production of myofibrils, mitochondria, sarcoplasmic reticulum, and other organelles

163
Q

Q: What causes muscular hypertrophy?

A

A: Forceful repetitive muscle activity, strength training, growth hormone during childhood, and testosterone

164
Q

Q: What are myofibrils?

A

A: Tiny contractile threads (2 µm in diameter) in muscle fiber sarcoplasm that give muscles their striped appearance

165
Q

Q: What is the sarcoplasmic reticulum’s role?

A

A: Stores calcium ions in relaxed muscles and releases them to initiate muscle contraction

166
Q

Q: What is muscular atrophy?

A

A: Decrease in size of muscle fibers due to loss of myofibrils

167
Q

Q: What are the two main types of muscular atrophy?

A

A: Disuse atrophy and denervation atrophy

168
Q

Q: What is disuse atrophy?

A

A: Occurs when muscles aren’t used (e.g., in bedridden patients); is reversible with exercise

169
Q

Q: What is denervation atrophy?

A

A: Occurs when nerve supply is cut off; muscles shrink to 1/4 original size; is irreversible and muscle is replaced by connective tissue

170
Q

Q: What is a triad in muscle structure?

A

A: A structure formed by terminal cisterns of the sarcoplasmic reticulum connecting with T tubules

171
Q

Q: What muscle changes occur between ages 30-50?

A

A: 10% of muscle tissue is replaced by fat and fibrous connective tissue

172
Q

Q: What muscle changes occur between ages 50-80?

A

A: An additional 40% of muscle tissue is replaced (total loss up to 50% of original muscle mass)

173
Q

Q: What is fibrosis?

A

A: The process where fibroblasts synthesize collagen fibers and extracellular matrix materials to form scar tissue

174
Q

Q: What are three main consequences of age-related muscle changes?

A

A: 1. Decreased muscle strength and flexibility 2. Slower reflexes 3. Increase in slow oxidative fibers

175
Q

Q: How does aging affect muscle fiber composition?

A

A: More Type I (slow-twitch) fibers and fewer fast-twitch fibers develop

176
Q

Q: What is sarcopenia?

A

A: Age-related muscle loss

177
Q

Q: How do skeletal muscle fibers switch between activity levels?

A

A: They switch between low activity (relaxed, using little ATP) and high activity (contracting, using ATP quickly).

178
Q

Q: How long does the ATP available in muscles last?

A

A: Only a few seconds.

179
Q

Q: What are the three methods muscles use to generate more ATP?

A

A:
1. Creatine phosphate (unique to muscles)
2. Anaerobic glycolysis (no oxygen needed)
3. Aerobic respiration (uses oxygen)

180
Q

Q: What is the primary purpose of ATP in muscles?

A

A: It is needed for muscle contraction, calcium pumping, and other processes.

181
Q

Q: What happens to extra ATP in relaxed muscles?

A

A: It is used to create creatine phosphate, an energy-rich molecule stored in muscles.

182
Q

Q: What enzyme transfers a phosphate group from ATP to creatine to form creatine phosphate?

A

A: Creatine Kinase (CK).

183
Q

Q: How does creatine phosphate provide energy during muscle contraction?

A

A: Creatine kinase transfers the phosphate from creatine phosphate to ADP, rapidly creating ATP.

184
Q

Q: How long can ATP and creatine phosphate energy stores sustain maximum effort?

A

A: About 15 seconds.

185
Q

Q: What is the top reaction in biologic work?

A

A: ATP is broken down into ADP and phosphate (P) by ATPase, releasing energy for biological work like muscle contraction.

186
Q

Q: What is the bottom reaction in biologic work?

A

A: Creatine phosphate donates its phosphate to ADP to produce ATP, catalyzed by creatine kinase.

187
Q

Q: What happens if creatine phosphate levels drop during high-intensity exercise?

A

A: ATP production decreases, limiting muscle performance.

188
Q

Q: How can creatine supplementation help during intense exercise?

A

A: It can increase creatine phosphate levels by 20%, enhancing ATP production and improving performance.

189
Q

Q: What happens when creatine phosphate stores are depleted?

A

A: Glucose is broken down into pyruvic acid via glycolysis to generate ATP.

190
Q

Q: Where does glucose come from for muscle energy?

A

A: From the blood or stored glycogen in muscles.

191
Q

Q: What happens during glycolysis?

A

A: Glucose is broken down into two pyruvic acid molecules, producing 2 ATPs, without requiring oxygen (anaerobic process).

192
Q

Q: What happens to pyruvic acid when oxygen is low?

A

A: It is converted into lactic acid, which enters the blood.

193
Q

Q: How does the liver handle lactic acid?

A

A: The liver converts some lactic acid back into glucose, reducing blood acidity.

194
Q

Q: What can lactic acid buildup cause?

A

A: Muscle soreness.

195
Q

Q: How long can anaerobic glycolysis provide energy?

A

A: About 2 minutes of intense activity.

196
Q

Q: How does anaerobic glycolysis compare to aerobic respiration?

A

A: It is faster but produces less ATP.

197
Q

Q: What happens to pyruvic acid when oxygen is available?

A

A: It enters the mitochondria for aerobic respiration, producing ATP, carbon dioxide, water, and heat.

198
Q

Q: What are the two stages of aerobic respiration?

A

A: The Krebs cycle and the electron transport chain.

199
Q

Q: How much ATP does aerobic respiration generate?

A

A: About 30–32 ATP molecules per glucose molecule.

200
Q

Q: Where do muscles get oxygen for aerobic respiration?

A

A: From hemoglobin in the blood and myoglobin in muscle fibers.

201
Q

Q: How does aerobic respiration compare to anaerobic glycolysis?

A

A: It is slower but produces much more ATP.

202
Q

Q: What fuel sources does aerobic respiration use?

A

A: Pyruvic acid, fatty acids, and amino acids.

203
Q

Q: What are the byproducts of aerobic respiration?

A

A: Carbon dioxide (CO₂), water (H₂O), and heat.

204
Q

Q: How long can aerobic respiration provide energy?

A

A: For several minutes to hours, depending on the activity.

205
Q

Q: What is rigor mortis?

A

A: The stiffening of muscles after death where muscles cannot contract or stretch, due to locked cross-bridges between myosin and actin.

206
Q

Q: What causes rigor mortis to begin?

A

A: Cellular membranes become leaky, causing calcium ions to leak from the sarcoplasmic reticulum into the sarcoplasm.

207
Q

Q: Why can’t muscles relax during rigor mortis?

A

A: ATP synthesis stops after death, so cross-bridges cannot detach from actin (muscle relaxation requires ATP).

208
Q

Q: How long do fibers remain contracted in rigor mortis?

A

A: Until myofilaments decay.

Kin 267 (Phys. 1) (17 decks)

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