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Exercise Physiology > Chapter 8 > Flashcards

Chapter 8 Flashcards

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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
CNS controls
brain and spinal cord
26
somatic motor neurons of PNS
responsible for carrying neural messages from spinal cord to skeletal muscles
27
motor unit
motor neuron and all the muscle fibers it innervates
28
neuromuscular junction
junction between motor neuron and muscle fiber
29
motor end plate
pocket formed around motor neuron by sarcolemma where NT release occurs
30
myofibrils can be further subdivided into
individual sarcomeres
31
sarcomeres
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)
32
thin filament consists of
actin, tropomyosin, troponin
33
thick filament consists of
myosin
34
the sliding filament model
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
35
sarcomere shortening during muscle contraction involves
reduction in the distance between Z lines of the sarcomere
36
what happens to the width of the A band with a concentric contraction
does not change
37
what happens to the width of the H-zone with a concentric contraction
decreases
38
what happens to the width of the I band with a concentric contraction
decreases
39
what happens to the width of the sarcomere with a concentric contraction
decreases
40
what happens to the width of the thin and thick filaments with a concentric contraction
does not change
41
what is required for muscle contraction
ATP
42
how do we acquire ATP for a muscle contraction
Myosin ATPase breaks down ATP as fiber contracts (ATP breakdown -> power stroke -> ADP + Pi)
43
breakdown of ATP equation
ATP+water --> (via ATPase)---> ADP +Pi + energy
44
sources of ATP for muscle contraction
ATP-Pc system Glycolysis Oxidative Phosphorylation
45
7 stages of cross bridge cycling
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
muscle cramps
aka spasmodic, involuntary muscle contractions often associated with prolonged, high intensity exercise (but not always)
47
electrolyte depletion and dehydration theory - muscle cramps
water and sodium loss via sweating causes spontaneous muscle contractions more likely in a hot environment
48
what are some limitations of the electrolyte depletion and dehydration theory to explain muscle cramps?
1) altered neuromuscular control theory 2)increased muscle spindle activity 3) decreased golgi tendon organ activity
49
altered neuromuscular control theory
abnormal spinal reflex due to fatigue results in increased excitatory activity of muscle spindles and reduced inhibitory effect of Golgi tendon organ
50
increased muscle spindle activity
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
decreased golgi tendon organ activity
*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
what helps muscle cramps
passive stretching activates golgi tendon organ inhibits motor neurons in spinal cord, resulting in muscle relaxation
53
type I fiber primary pathway for ATP synthesis
aerobic
54
type IIa fiber primary pathway for ATP synthesis
combination of aerobic and anaerobic
55
type IIx fiber primary pathway for ATP synthesis
anaerobic
56
Type I myoglobin content/# of mitochondria
high
57
Type IIa myoglobin content/# of mitochondria
intermediate
58
Type IIx myoglobin content/# of mitochondria
low
59
Type I speed of contraction
slow
60
Type IIa speed of contraction
fast
61
Type IIx speed of contraction
fastest
62
Type I maximal force production and power output
moderate
63
Type IIa maximal force production and power output
high
64
Type IIx maximal force production and power output
highest
65
Type I rate of fatigue
slow
66
Type IIa rate of fatigue
intermediate
67
Type IIx rate of fatigue
fast
68
Type I type of motor unit innervating muscle
type S
69
Type IIa type of motor unit innervating muscle
type FR
70
Type IIx type of motor unit innervating muscle
type FF
71
recruitment order of muscle fibers
1st- Type I 2nd- Type IIa 3rd- Type IIx
72
activities best suited for Type I muscle fibers
endurance type fibers (slow fatigue rate)
73
activities best suited for Type IIa and IIx muscle fibers
power type activities
74
how are skeletal muscle fibers typed
via muscle biopsy (small piece of muscle removed - may not be representative of entire body)
75
characteristics of type I fibers
slow twitch fibers slow-oxidative fibers
76
characteristics of type IIa fibers
intermediate fibers fast-oxidative glycolytic fibers
77
characteristics of type IIx fibers
fast twitch fibers fast-glycolytic fibers
78
speed of shortening is greater in
fast fibers SR releases Ca2+ at a faster rate higher ATPase activity
79
force production: larger vs smaller fibers
larger muscle fibers produce more force than smaller fibers because they have more actin and myosin than small fibers
80
men have significantly greater___
total, upper body, and lower body skeletal muscle mass
81
who generates more absolute force production (men or women)
men generate more absolute force production
82
power output between fiber type equation
power= force x shortening velocity
83
sprinters have more
fast fibers power athletes
84
distance runners have more
slow fibers endurance athletes
85
force regulation in muscle
1) types and number of motor units recruited 2) initial muscle length 3) nature of neural stimulation of motor units
86
more motor units =
greater force
87
fast motor units =
greater force
88
recruitment pattern of motor units during graded exercise
Type S then Type FR then type FF (generate the most force)
89
progressive recruitment of motor units begins with
smallest motor units and progressing to larger and larger motor neurons
90
increasing stimulus strength recruits more
motor units and produces more force
91
normal body movements involve sustained contractions that are
NOT simple twitches
92
muscle twitch
contraction as the result of a single stimulus
93
increasing the frequency of the stimulus results in
summation of the twitches and tetanus
94
DOMS
delayed onset muscle soreness appears 24-48 hours after strenuous exercise due to microscopic tears in muscle fibers or connective tissue
95
what causes more damage: concentric or eccentric exercises
eccentric exercise causes more damage than concentric exercise
96
exercise induced muscle injury
sarcomere damage (Hrs to Days) immune cell infiltration (Days) satellite cell activation (Days to Weeks)
97
how do muscle fibers repair themselves
using resident satellite populations
98
procedures leading to DOMS
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
a bout of unfamiliar exercise results in
DOMS
100
following recovery of DOMS
another bout of same exercise results in minimal injury

Exercise Physiology (8 decks)

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