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Exercise Physiology > Skeletal Muscle > Flashcards

Skeletal Muscle Flashcards

1
Q

Subsarcolemmal mitochondria purpose

A

Produce cellular energy needed to maintain active transport of ions across the sarcolemma

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2
Q

Intermyofibrillar mitochondria purpose

A

Provides energy to sustain muscle contraction

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3
Q

Where is the subsarcolemmal mitochondria located

A

Directly beneath the cell membrane

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4
Q

Where is the intermyofibrillar mitochondria located

A

Near the myofibrillar (contractile) proteins

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5
Q

5 components of muscles

A

Muscle —> fascicle —> muscle fibers —> myofibrils —> sarcomere

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6
Q

Thin filament

A

Actin

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7
Q

Thick filament

A

Myosin

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8
Q

Satellite cells

A

Produce more muscle fibers through myoblasts

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9
Q

How do satellite cells aid in muscle growth and repair

A

They increase the number of nuclei to allow for greater protein synthesis

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10
Q

Hypertrophy

A

Increase in muscle size by adding muscle fibers

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11
Q

Result of going from trained to untrained

A

Increased amount of nuclei remains even though the muscle is smaller. Allows for hypertrophy to happen faster

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12
Q

3 basic functions of skeletal muscles

A
  1. locomotion and breathing 2. Postural support 3. Heat production during cold stress
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13
Q

How is the muscle considered an endocrine gland?

A

Skeletal muscle produces myokines during contractions

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14
Q

Myokines role in glucose

A

Stimulate glucose uptake and promote liver glucose production

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15
Q

Myokines role in fat

A

Stimulate fatty acid oxidation and triglyceride breakdown

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16
Q

Myokines role in blood vessels

A

They promote blood vessel growth in the muscle

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17
Q

Interleukin 6 (IL-6)

A

Pro-inflammatory and anti-inflammatory; Produced during exercise and promotes anti-inflammatory effects.

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18
Q

Static muscle movement

A

Muscle exerts force without changing length (isometric)

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19
Q

Concentric

A

Muscle shortened during force production

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20
Q

Eccentric

A

Muscle lengthens during force production (results in soreness typically)

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21
Q

Somatic nervous system

A

Responsible for controlling skeletal muscle

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22
Q

Somatic motor neurons role

A

Carry neural messages from spinal cord to skeletal muscles

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23
Q

Neuromuscular junction

A

Connection point between motor neuron and muscle fiber

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24
Q

Motor end plate

A

Pocket around motor neurons by sarcolemma

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25
How does muscle shortening occur
From movement of thin actin filament over thick myosin filament forming cross-bridges
26
What happens to the z line during muscle contraction
As the sarcomere shortens, the distance between the spines of the sarcomere shorten
27
During a biceps curl, what shortens within the biceps brachii sarcomeres
the h zone and the I band
28
What remains the same in a muscle contraction
The m line, the a zone
29
Where does the energy for muscle contraction come from?
Myosin ATPase breaks down ATP as fiber contracts. This releases ADP and Phosphate with energy
30
5 steps of excitation coupling
1. Action potential stimulates Ach at neuromuscular junction 2. Ach induces action potential in muscle fiber down t tubule 3. Action potential releases Ca2+ from SR 4. Ca2+ initiates troop myosin displacement to reveal myosin binding sites 5. Myosin forms cross bridges with actin producing force
31
What does calcium bind to in the muscle
The troponin
32
What happens when calcium binds to troponin
Tropomyosin moves revealing binding site
33
What type of exercise are muscle cramps associated with?
Prolonged high intensity
34
Electrolyte depletion and dehydration theory
Sweating increases water and sodium loss which causes muscle cramps. More likely in hot environment
35
What are limitations to the electrolyte depletion and dehydration theory on muscle cramps?
It doesn’t explain for how cramps are localized
36
Neuromuscular control theory
Abnormal spinal reflex activity due to fatigue
37
How does fatigue cause abnormal spinal reflex activity
increased excitatory activity of muscle spindles and reduced inhibitory effect of golgi tendon organ
38
Muscle spindle role
Detect stretch of the muscle
39
Golgi tendon organ role
Causes muscle to relax
40
How does passive stretching relieve muscle cramps
Activated the golgi tendon organ to inhibit motor neurons in the spinal cord resulting in muscle relaxation
41
TRP channels
When activated, send inhibitory signals to the spinal cord to inhibit overactive motor neurons that cause cramping
42
4 steps of muscle spindle activity
1. Spindle detect stretch 2. Sensory neurons send AP to spinal cord 3. Sensory neurons synapse with alpha motor neurons 4. Stimulation of alpha motor neurons causes the muscles to contract and resist being stretched
43
Type 1 fibers
Slow twitch fibers; oxidative fibers
44
Type IIa fibers
Immediate fibers; fast-oxidative glycolytic fibers
45
Type IIx
Fast twitch fibers; fast-glycolytic fibers
46
Which fibers have the most mitochondria
Slow type I fibers> type IIa> type IIx
47
Which fibers are most resistent to fatigue
Slow type 1> type IIa > type IIx
48
Predominant energy system for Type I fibers
Aerobic
49
Predominant energy system to type IIa fibers
Combo in aerobic and anaerobic
50
Predominant energy system for type IIx fibers
Anaerobic
51
Increased number of capillaries means
More oxygen and blood delivered to muscle fibers
52
Mitochondria is associated with
Oxygen to generate ATP. More mitochondria means more oxidative slower to fatigue type 1 fibers
53
What delivers oxygen to mitochondria
Myoglobin
54
Which fibers break down ATP the fastest?
Fast fibers break down ATP faster and have higher ATPace activity Type IIx> Type IIa> Type I
55
What is the speed of contraction (Vmax) dependent on?
Myosin ATPase activity. The faster the sarcoplasmic reticulum releases Ca2+ will increase ATPase activity. Fast fibers are more efficient at this
56
Why do larger muscle fibers produce more force
They have more actin and myosin than small fibers do.
57
Which muscle fiber types have the greatest speed
Type IIx > type IIa > type I due to size
58
Power in relation to muscle contraction
Power = force x shortening velocity Fast fibers have a higher shortening velocity and greater force due to size and number of actin and myosins
59
Which muscle fibers are more efficient at generating force
Fast fibers use more ATP to generate force than slow type I fibers do so they are less efficient
60
Type of fibers in power athletes
Higher % of fast fibers
61
Fiber type in endurance athletes
Higher % in slow fibers
62
What amount of motor units produce more force
The more motor units recruited, the more force generated
63
What motor unit speed generates greater force?
Faster motor units
64
Type s motor units
the smallest of the motor neurons; innervate type 1(slow) muscle fibers
65
Type FR motor units
(Fatigue resistant) innervate type IIa muscle fibers
66
Type FF motor units
(Fast , fatiguable) Largest motor unit; innervate type IIx muscle fibers
67
What is the motor unit recruitment pattern during graded exercise
Type s —> type Fr —> type FF
68
What is the muscle fiber type recruitment pattern in graded exercise
Type I —> type IIa —> type IIx
69
How does increasing stimulus produce more force
Increasing stimulus (increasing weight) recruits more motor units
70
What muscle length produces the most force
Whichever length has the ability for the most cross bridge formations
71
Why is force production additive
Increases Ca2+ availability allows for more contraction coupling
72
Why can’t we assume muscle soreness is a result of Lactic acid?
Lactate removal happens within 60 minutes post exercise and soreness doesn’t always result after repetitive training
73
Delayed onset muscle soreness
24-48 hrs post; microscopic teases in muscle fibers or connective tissues; eeccentric
74
What is responsible for soreness within hours
Sarcomere damage
75
What is responsible for soreness following days
Immune cell infiltration
76
What is responsible for soreness days to weeks post exercise
Satellite cell activation causing hypertorphy
77
6 steps of DOMS
1. Structural damage to muscle fibers 2. Membrane damage 3. Calcium leaks out of SR 4. Cellular breakdown of proteins 5. Inflammatory response 6. Edema and pain

Exercise Physiology (12 decks)

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