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Exercise Physiology > Chapter 8 > Flashcards

Chapter 8 Flashcards

1
Q

human body contains over how many skeletal muscles and what do they weigh

A

over 600 skeletal muscles that way 40-50% body weight

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2
Q

how are skeletal muscles attached to bones

A

through connective tissue called tendons

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3
Q

origin

A

the end of the muscle that is attached to bone and DOES NOT move

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4
Q

insertion

A

the opposite end to the origin that is moved during a muscular contraction

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5
Q

structure of skeletal muscle- superficial to deep

A

muscle
muscle bundle
fascicle
muscle fiber
myofibril
sarcomere with thick and thin filaments

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6
Q

major organelles within a muscle cell

A

have many nuclei along the entire length of the muscle fiber
lots of mitochondria

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7
Q

2 subpopulations of mitochondria in skeletal muscle

A

subsarcolemmal (SS) mitochondria
intermyofibrillar (IMF) mitochondria

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8
Q

subsarcolemmal (SS) mitochondria

A

located directly beneath cell membrane (sarcolemma)
produce cellular energy needed to maintain active transport of ions across the sarcolemma

*needs to establish a [ ] gradient with action potentials to be able to propagate along the surface

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9
Q

intermyofibrillar (IMF) mitchondria

A

next to contractile proteins (myofibrillar proteins)
provide energy needed to sustain muscle contraction

*supply ATP so we can get myosin head to release from actin

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10
Q

satellite cells

A

play a role in muscle growth and repair - during muscle growth, satellite cells increase the # of nuclei which helps with hypertrophy (increasing the size of the muscle fiber)

more nuclei allow for greater protein synthesis which is important for muscle growth in response to strength training

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11
Q

3 functions of skeletal muscle

A

1) force production for locomotion and breathing
2) force production for postural support
3) heat production during cold stress (shivering thermogenesis)

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12
Q

what is produced in skeletal muscle as a result of contractions

A

myokines and cytokines

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13
Q

role of myokines in skeletal muscle contraction

A

stimulate glucose uptake and fatty acid oxidation
promote blood vessel growth in muscle
promote liver glucose production and triglyceride breakdown

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14
Q

role of cytokines during skeletal muscle contraction

A

might have a pro-inflammatory response

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15
Q

as you increase the duration of an exercise, what happens to myokine production during skeletal muscle contraction

A

increase duration
increase myokines
increase glucose uptake and fat oxidation
*crossover effect (switch from CHO to FATs as duration increases)

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16
Q

what is the main cytokine produced during a skeletal muscle contraction

A

IL6
both pro-inflammatory and anti-inflammatory

*IL6 produced during exercise promotes anti-inflammatory effect

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17
Q

regular exercise promotes a anti-inflammatory environment by

A

reducing chronic inflammation and reduced risk of heart disease, type 2 diabetes, and certain cancers

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18
Q

flexors

A

decrease joint angle

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19
Q

extensors

A

increase joint angle

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20
Q

static

A

not changing the angle of a joint
muscle exerts force without changing length
pulling against immovable object
postural muscles

ex) pressing on a well

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21
Q

types of dynamic muscle contractions

A

concentric and eccentric

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22
Q

concentric contraction

A

muscle shortens during force production

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23
Q

eccentric contraction

A

muscle produces force but length increases
associated with muscle fiber injury and soreness (growth and repair)

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24
Q

PNS controls

A

everything other than brain and spinal cord

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25
Q

CNS controls

A

brain and spinal cord

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26
Q

somatic motor neurons of PNS

A

responsible for carrying neural messages from spinal cord to skeletal muscles

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27
Q

motor unit

A

motor neuron and all the muscle fibers it innervates

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28
Q

neuromuscular junction

A

junction between motor neuron and muscle fiber

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29
Q

motor end plate

A

pocket formed around motor neuron by sarcolemma
where NT release occurs

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30
Q

myofibrils can be further subdivided into

A

individual sarcomeres

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31
Q

sarcomeres

A

contain specialized arrangement of thin and thick filaments
includes: Z line, M line, I band (light zone), A band (dark zone), H zone (middle of A band)

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32
Q

thin filament consists of

A

actin, tropomyosin, troponin

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33
Q

thick filament consists of

A

myosin

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34
Q

the sliding filament model

A

muscle shortening occurs due to the movement of the thin (actin) filament over the thick (myosin) filament

formation of cross bridges between thick and thin filaments (myosin head has to hold onto actin to pull it together towards the M line) - * in order to move actin over, cross bridge must be formed

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35
Q

sarcomere shortening during muscle contraction involves

A

reduction in the distance between Z lines of the sarcomere

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36
Q

what happens to the width of the A band with a concentric contraction

A

does not change

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37
Q

what happens to the width of the H-zone with a concentric contraction

A

decreases

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38
Q

what happens to the width of the I band with a concentric contraction

A

decreases

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39
Q

what happens to the width of the sarcomere with a concentric contraction

A

decreases

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40
Q

what happens to the width of the thin and thick filaments with a concentric contraction

A

does not change

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41
Q

what is required for muscle contraction

A

ATP

42
Q

how do we acquire ATP for a muscle contraction

A

Myosin ATPase breaks down ATP as fiber contracts

(ATP breakdown -> power stroke -> ADP + Pi)

43
Q

breakdown of ATP equation

A

ATP+water –> (via ATPase)—> ADP +Pi + energy

44
Q

sources of ATP for muscle contraction

A

ATP-Pc system
Glycolysis
Oxidative Phosphorylation

45
Q

7 stages of cross bridge cycling

A

1)Action potential stimulates ACh release from alpha motor neuron at neuromuscular junction
2) ACh induces an action potential in the muscle fiber. Action potential spreads down sarcolemma and T tubules. Myosin binding sites on the actin molecule are covered in resting fibers (tropomyosin intertwined with actin)
3) the action potential releases Ca2+ from sarcoplasmic reticulum
4) calcium binds troponin on tropomyosin. Tropomyosin moves, revealing myosin binding sites.
5) cross bridge forms when myosin head (with ADP + Pi bound) binds actin
6) myosin head pivots (with ADP + Pi bound) (power stroke), moving actin. ADP and Pi dissociate from myosin head
7) myosin head releases actin when a fresh ATP binds to the myosin head allowing myosin head to release from actin
8) myosin head binds next actin. The ATP on myosin head is cleaved to ADP + Pi and cycle repeats

46
Q

muscle cramps

A

aka spasmodic, involuntary muscle contractions

often associated with prolonged, high intensity exercise (but not always)

47
Q

electrolyte depletion and dehydration theory - muscle cramps

A

water and sodium loss via sweating causes spontaneous muscle contractions
more likely in a hot environment

48
Q

what are some limitations of the electrolyte depletion and dehydration theory to explain muscle cramps?

A

1) altered neuromuscular control theory
2)increased muscle spindle activity
3) decreased golgi tendon organ activity

49
Q

altered neuromuscular control theory

A

abnormal spinal reflex due to fatigue
results in increased excitatory activity of muscle spindles and reduced inhibitory effect of Golgi tendon organ

50
Q

increased muscle spindle activity

A

1) muscle spindles detect stretch of the muscle
2) sensory neurons conduct action potentials to the spinal cord in order to get muscle to contract
3) sensory neurons synapse with alpha motor neurons
4) stimulation of the alpha motor neurons causes the muscle to contract and resist being stretched

51
Q

decreased golgi tendon organ activity

A

*make it easier to hold contraction and causes cramps

Muscle contraction increases tension applied to tendons:
1) golgi tendon organ detects tension applied to a tendon
2) sensory neurons conduct action potentials to the spinal cord
3) sensory neurons synapse with inhibitory interneurons that synapse with alpha motor neurons
4) inhibition of alpha motor neurons causes muscle relaxation, relieving the tension applied to the tendon

52
Q

what helps muscle cramps

A

passive stretching
activates golgi tendon organ inhibits motor neurons in spinal cord, resulting in muscle relaxation

53
Q

type I fiber primary pathway for ATP synthesis

A

aerobic

54
Q

type IIa fiber primary pathway for ATP synthesis

A

combination of aerobic and anaerobic

55
Q

type IIx fiber primary pathway for ATP synthesis

A

anaerobic

56
Q

Type I myoglobin content/# of mitochondria

A

high

57
Q

Type IIa myoglobin content/# of mitochondria

A

intermediate

58
Q

Type IIx myoglobin content/# of mitochondria

A

low

59
Q

Type I speed of contraction

A

slow

60
Q

Type IIa speed of contraction

A

fast

61
Q

Type IIx speed of contraction

A

fastest

62
Q

Type I maximal force production and power output

A

moderate

63
Q

Type IIa maximal force production and power output

A

high

64
Q

Type IIx maximal force production and power output

A

highest

65
Q

Type I rate of fatigue

A

slow

66
Q

Type IIa rate of fatigue

A

intermediate

67
Q

Type IIx rate of fatigue

A

fast

68
Q

Type I type of motor unit innervating muscle

A

type S

69
Q

Type IIa type of motor unit innervating muscle

A

type FR

70
Q

Type IIx type of motor unit innervating muscle

A

type FF

71
Q

recruitment order of muscle fibers

A

1st- Type I
2nd- Type IIa
3rd- Type IIx

72
Q

activities best suited for Type I muscle fibers

A

endurance type fibers (slow fatigue rate)

73
Q

activities best suited for Type IIa and IIx muscle fibers

A

power type activities

74
Q

how are skeletal muscle fibers typed

A

via muscle biopsy
(small piece of muscle removed - may not be representative of entire body)

75
Q

characteristics of type I fibers

A

slow twitch fibers
slow-oxidative fibers

76
Q

characteristics of type IIa fibers

A

intermediate fibers
fast-oxidative glycolytic fibers

77
Q

characteristics of type IIx fibers

A

fast twitch fibers
fast-glycolytic fibers

78
Q

speed of shortening is greater in

A

fast fibers
SR releases Ca2+ at a faster rate
higher ATPase activity

79
Q

force production: larger vs smaller fibers

A

larger muscle fibers produce more force than smaller fibers because they have more actin and myosin than small fibers

80
Q

men have significantly greater___

A

total, upper body, and lower body skeletal muscle mass

81
Q

who generates more absolute force production (men or women)

A

men generate more absolute force production

82
Q

power output between fiber type equation

A

power= force x shortening velocity

83
Q

sprinters have more

A

fast fibers

power athletes

84
Q

distance runners have more

A

slow fibers

endurance athletes

85
Q

force regulation in muscle

A

1) types and number of motor units recruited
2) initial muscle length
3) nature of neural stimulation of motor units

86
Q

more motor units =

A

greater force

87
Q

fast motor units =

A

greater force

88
Q

recruitment pattern of motor units during graded exercise

A

Type S then Type FR then type FF (generate the most force)

89
Q

progressive recruitment of motor units begins with

A

smallest motor units and progressing to larger and larger motor neurons

90
Q

increasing stimulus strength recruits more

A

motor units and produces more force

91
Q

normal body movements involve sustained contractions that are

A

NOT simple twitches

92
Q

muscle twitch

A

contraction as the result of a single stimulus

93
Q

increasing the frequency of the stimulus results in

A

summation of the twitches and tetanus

94
Q

DOMS

A

delayed onset muscle soreness
appears 24-48 hours after strenuous exercise
due to microscopic tears in muscle fibers or connective tissue

95
Q

what causes more damage: concentric or eccentric exercises

A

eccentric exercise causes more damage than concentric exercise

96
Q

exercise induced muscle injury

A

sarcomere damage (Hrs to Days)
immune cell infiltration (Days)
satellite cell activation (Days to Weeks)

97
Q

how do muscle fibers repair themselves

A

using resident satellite populations

98
Q

procedures leading to DOMS

A

strenuous exercise
structural damage to muscle fibers
membrane damage
CA2+ leaks out of SR
protease activation resulting in breakdown of cellular proteins
inflammatory response
edema and pain

99
Q

a bout of unfamiliar exercise results in

A

DOMS

100
Q

following recovery of DOMS

A

another bout of same exercise results in minimal injury

Exercise Physiology (8 decks)

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