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Human Physiology > Muscle > Flashcards

Muscle Flashcards

1
Q

what are the 3 types of muscle?

A

skeletal, cardiac, smooth

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2
Q

this type of muscle is striated, voluntary, and attached to bone

A

skeletal

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3
Q

this type of muscle of striated, involuntary, and in the heart

A

cardiac

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4
Q

this type of muscle is not striated, involutory, and lines hollow organs

A

smooth

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4
Q

as muscles contract, _____ is generated and this is thermogenesis

A

heat

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4
Q

motor neurons are found in ____ matter of the spinal cord

A

gray

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5
Q

what connects muscle to bone?

A

tendon

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5
Q

______ is a bundle of muscle fascicles

A

muscle

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5
Q

____ _____ are a bundle of muscle fibers/cells

A

muscle fascicle

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6
Q

_____ are a contractile assemble of proteins in a muscle cell

A

myofibrils

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7
Q

_____ are contracting subunits that make up myofibrils

A

sarcomere

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8
Q

___ _____ is the intracellular storehouse of calcium ions

A

sarcoplasmic reticulum

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9
Q

____ ____ are a network of tubular passages within striated muscle that are an extension of the plasma membrane

A

transverse tubules

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10
Q

____ is the primary protein of thin filament

A

actin

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11
Q

_____ is the primary protein of thick filament

A

myosin

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12
Q

myosin is driven by ___ to allow for muscle contraction

A

ATP

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13
Q

____ blocks myosin binding sites on thin filament during relaxation

A

tropomyosin

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14
Q

there are ___ actin subunits per tropomyosin molecule

A

7

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15
Q

____ is the calcium sensor that triggers muscle contraction and locks tropomyosin in place when the muscle is relaxed

A

troponin

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16
Q

troponin is ____ subunits long and is on the ___ filament

A

3, thin

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17
Q

____ is a spring-like connector of the thick filaments to the Z disc

A

titin

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18
Q

__-_____ is the primary structural protein of the Z-disc

A

alpha-actinin

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19
Q

______ is the primary structural proteins of the M-line

A

myomesin

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20
Q

____ connects the Z- disc to the membrane cytoskeleton and is associated with muscular dystrophy

A

dystrophin

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21
Q

_____ is the “template” for actin filament length

A

nebulin

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22
Q

what are the 2 contractile proteins?

A

actin, myosin

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23
Q

what are the 2 muscle regulatory proteins?

A

tropomyosin, troponin

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24
Q

what is the synapse between a somatic motor neuron and a skeletal muscle fiber called?

A

neuromuscular junction (NMJ)

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25
Q

in the end plate potential, depolarization is generated at the muscle membrane due to the binding of what?

A

Ach

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26
Q

the binding of ACh at the end plate potential triggers an ___ ____ if the EPP exceeds the threshold of the voltage-gated sodium channels

A

action potential

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27
Q

an action potential is generated at the NMJ if the ____ exceeds the threshold for the __ ___ ___ ____

A

EPP, voltage gated sodium channel

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28
Q

what part of the NMJ is the post-synaptic portion?

A

motor end plate

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29
Q

the motor end plate has ____ receptors and ligand gated channels

A

ACh

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30
Q

_____ is at the motor end plate and degrades Ach after a signal is sent to the muscle and clears the synapse for a new signal

A

acetylcholinesterase

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31
Q

muscle action potentials are ______ than nerves because of the different proteins

A

longer

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32
Q

action potentials in muscles track along the _____

A

membrane

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33
Q

what is the term for the junction of the transverse tubule with the sarcoplasmic reticulum?

A

triad

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34
Q

what receptor on the membrane surface is:
-L type votage-gated calcium channel
-found in T-tubule membrane
-moves in response to action potentials/voltage sensor

A

DHP

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35
Q

what receptor on the membrane surface is:
-calcium release channel
-found in the SR membrane
-opens to release calcium when the DHP receptor moves

A

RyR

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36
Q

what on the cell membrane:
-is found in the SR membrane
-pumps calcium into the SR against it’s concentration gradient
-takes calcium back into the SR via active transport

A

SR calcium-ATPase

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37
Q

during the contraction of skeletal muscle fibers, the width of the __ band does not change but the width of the ___ band narrows

A

A, I

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38
Q

in the sliding filament mechanism, the _____ filaments slide inwards towards the center of the sarcomere

A

thin

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39
Q

in the sliding filament mechanism, myosin heads attach to ____ filaments and pull them in both halves of the sarcomereno

A

thin

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40
Q

in the sliding filament mechanism, do the individual lengths of thick and thin filaments change?

A

no

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41
Q

in the sliding filament mechanism, what two things does contraction result in?

A

z-discs coming closer, sarcomeres shorten

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42
Q

what two things does sarcomere shortening lead to in the sliding filament mechanism?

A

myofibril shortening, whole muscle shortening

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43
Q

what molecule leads to shortening and contraction of muscle?

A

calcium

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44
Q

in the contraction cycle, what occurs so that myosin is energized and perpendicular to the thin filament?

A

ATP hydrolysis

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45
Q

in the contraction cycle, what is the crossbridge?

A

myosin head attaches to the binding site on actin and the phosphate group is released

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46
Q

in the contraction cycle, describe the power stroke

A

myosin head pivots and pull the thin filament towards the center of the sarcomere, generating force and ADP is released

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47
Q

in the contraction cycle, what causes the crossbridge to detach for actin?

A

actin binds to another ATP and myosin heads detach

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48
Q

in simple terms, outline the contraction cycle

A
  1. myosin bind ATP and becomes energized
    2.myosin head binds to actin to form a crossbridge (energy is held onto)
  2. crossbridge pivots, pulling thin filament past the thick filament toward the center of the sarcomere (powerstroke)
  3. myosin heads bind to ATP, crossbridge detaches from actin
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49
Q

what action is needed to start the contraction cycle?

A

calcium released into sacroplasm

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50
Q

what two events occur for the relaxation phase of muscle?

A
  1. calcium pumps reaccumulate calcium into the SR
  2. troponin blocks binding site
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51
Q

troponin holds tropomyosin in position to block ______ -____ _____ on actin

A

myosin binding sites

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52
Q

Why does acetylcholinesterase destroy Ach?

A

so that another muscle action potential does not arise unless more Ach is released from the somatic motor neuron

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53
Q

in muscle contraction, a muscle potential travels along a ___ ____ and triggers a change in the ______ that causes calcium release channels to open and calcium ions go into the sarcoplasm

A

transverse tubule, DHR

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54
Q

after calcium is released into the sarcoplasm, it binds to ____ on the thin filament and exposes the myosin-binding sites on actin

A

troponin

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55
Q

how are calcium levels in the sarcoplasm restored?

A

calcium channels close, calcium ATase pump uses ATP to pump out back into the SR

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56
Q

what molecule blocks the myosin-binding sites on actin?

A

tropomyosin

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57
Q

what type of contraction:
-is the activation of muscle but shortening is prevented
-change in tension and rate of force development is measure

A

isometric

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58
Q

what type of contraction:
-activation of muscle when muscle shortening is allowed
-change in length and rate of shortening can be measured

A

isotonic

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59
Q

what are the two important components of the electrical stimulus that leads to skeletal muscle contraction?

A

amplitude (strength of signal)
frequency (rate of signaling)

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60
Q

what type of ATP production:
-one step reaction/fast
-transfers P from creatine-phosphate to ADP to regenerate ATP
-limited capacity

A

creatine kinase

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61
Q

what type of ATP production:
-multistep reaction
-anaerobic
-converts 1 glucose to 2 ATP

A

glycolysis

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62
Q

what type of ATP production:
-multistep reaction
-requires oxygen and mitochondria
-able to convert glucose to 36 ATP as well as fatty acids and amino acids into ATP

A

oxidative phosphorylation

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63
Q

what are the 3 muscle fiber types?

A

slow-oxidative, fast-oxidative, fast-glycolytic

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64
Q

what type of muscle fiber:
-red muscle
-small diameter
-slow myosin aerobic metabolism

A

slow-oxidative

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65
Q

what type of muscle fiber:
-red muscle
-intermediate diameter cells
-fast myosin, aerobic and anaerobic metabolism

A

fast-oxydative

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66
Q

what type of muscle fiber:
-white muscle
-large diameter cells
-anaerobic metabolism

A

fast-glycolytic

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67
Q

define a motor unit

A

motor neuron and the population of muscle fibers it innervates

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68
Q

during muscle fiber recruitment, as the load increased, the ____ of the motor units recruited increase

A

size

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69
Q

in what order are motor units recruited?

A

slow oxidative, fast oxidative, fast glycolytic

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70
Q

____ ____ provides a reservoir of high energy phosphate that accumulates during muscle cell rest

A

creatine kinase

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71
Q

creatine kinase provides ATP during the ___ ___ _____ of a contraction

A

first few seconds

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72
Q

what is ATP production in the cell limited by?

A

amount of creatine kinase stored in the cell

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73
Q

creatine kinase powers ___ ____ of muscle activity

A

short periods

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74
Q

glycolysis and/or oxidative phosphorylation during periods of rest can regenerate ___ _____ from ATP and creatine because the creatine kinase enzyme can run in reverse

A

creatine phosphate

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75
Q

what is described as a glucose polymer that is stored by muscle cells and the liver?

A

glycogen

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76
Q

glycolysis occurs during ___ intensity exercise and powers ____ periods of muscle activity

A

high, short

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77
Q

what type of ATP production powers extended periods of muscle activity?

A

oxidative phosphorylation

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78
Q

in oxidative phosphorylation, ____ is the major fuel for the first 5-10 minutes and _____ _____ are the next fuel

A

glycogen, fatty acids

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79
Q

how do muscles grow?

A

more myofibrils in the muscle cytoplasm

80
Q

slow-oxidative fibers use what type of ATP prouction?

A

oxidative phosphorylation

81
Q

slow-oxidative fibers are ____ resistant

A

fatigue

82
Q

postural muscles are what type of fiber?

A

slow-oxidative

83
Q

what type of ATP production is used by fast-oxidative fibers?

A

oxidative phosphorylation

84
Q

what type of ATP production is used by fast-glycolytic fibers?

A

glycolytic metabolism

85
Q

fast-glycolytic fibers are prone to ____

A

fatigue

86
Q

_____ is a prolonged contraction and allows us to walk

A

tetanus

87
Q

what 3 factors affect how much tension a whole muscle can produce?

A

-number of active motor units
-number of muscle fibers in each motor unit
-fiber types of the activated motor units

88
Q

what are the 4 potential causes of muscle fatigue?

A
  1. high extracellular K- depressed membrane potential and reduces excitability
  2. high intracellular ADP- inhibits crossbridge cycling
  3. calcium regulation disruption- insufficient calcium release
    4.acidification of sarcoplasm- myosin’s ATPase activity less in acid
89
Q

this describes what skeletal muscle’s fatigability:
-slow myosin ATPase
-least amount of tension
-less likely to fatigue

A

slow oxidative

90
Q

this describes what skeletal muscle’s fatigability:
-fast myosin ATPase
-moderative level of tension
-moderate likely to fatigue

A

fast oxidative

91
Q

this describes what skeletal muscle’s fatigability:
-fast myosin ATPase
-greatest amount of tension
-most likely to fatigue rapidly

A

fast glycolytic

92
Q

what is the effector of the somatic nervous system?

A

skeletal muscle

93
Q

what is the motor neuron pathway of the somatic nervous system?

A

-one neuron pathway
-single somatic motor neurons extends from CNS to synapse directly with effector

94
Q

what is the neurotransmitter of the somatic nervous system?

A

ACh

95
Q

what is the receptor type on the effector organ in the somatic nervous system?

A

cholinergic

96
Q

what is the action of the neurotransmitter on the effector on the somatic nervous system?

A

always excitatory causing contraction of skeletal muscle

97
Q

what controls the motor output in the somatic nervous system?

A

voluntary control from cerebral cortex, contributions from basal nuclei, cerebellum, brain stem, and spinal cord

98
Q

what are the four sources of input to lower motor neurons?

A
  1. local circuits in the brain stem and spinal cord
  2. upper motor neurons from brain stem
  3. basal nuclei
  4. cerebellum
99
Q

what source of input to lower motor neurons is the highest level of control?

A

upper motor neurons from cerebral cortex

100
Q

what sources of input to lower motor neurons are the middle level of control?

A

basal nuclei, cerebellum

101
Q

what source of input to lower motor neurons is the lowest level of control?

A

local circuits in brain stem and spinal cord

102
Q

what is the role of the sensory neuron in somatic reflex arches?

A

peripheral receptor

103
Q

what is the role of interneurons in the somatic reflex arches?

A

relax sensory information

104
Q

what is the role of the somatic motor neuron in somatic reflex arches?

A

integrating center and effector control

105
Q

what is the effector in the somatic reflex arches?

A

skeletal muscle

106
Q

what are the three sources of response for the somatic reflex arches?

A

pain, length of muscle change, excessive muscle tension

107
Q

____ ___ ____ arches may result in excitation or inhibition of alpha motor neurons

A

somatic reflex arches

108
Q

what are the two sensory receptors that trigger skeletal muscle reflex responses?

A

muscle spindles, golgi tendon organs

109
Q

__ ___ ____ are responsible for the control of involuntary movement that regulates posture, balance, muscle tone, and reflective movement of the head and trunk

A

upper motor neurons

110
Q

what is controlled by vestibular nuclei?

A

posture and balence

111
Q

what is controlled by the reticular formation?

A

posture and muscle tone during movements/ongoing movements

112
Q

the ___ ______ tract exists muscles in upper motor neuron pathways

A

medial reticulospinal

113
Q

the ____ _____ tract inhibits muscles in upper motor neuron pathways

A

lateral reticulospinal

114
Q

what is the role of the superior colliculus?

A

assist with movements of the heads, trunk, and eye movements through the tectospinal tract and respond to sudden or unexpected stimuli

115
Q

what tract is used by the superior colliculus?

A

tectospinal

116
Q

what is the role of red nucleus?

A

control precise voluntary movements of the upper limbs through the rubrospinal tract

117
Q

what tract is used by red nucleus?

A

rubrospinal

118
Q

what tract of the upper motor neuron tract:
-crosses body at medulla
-responsible for precise and agile movements of hands and feet

A

lateral corticospinal

119
Q

what tract of the upper motor neuron tract:
-crosses body at the spinal cord
-responsible for trunk and proximal parts of the limbs

A

ventral corticospinal

120
Q

what pathways of the upper motor neurons control facial expression, chewing, speech, and movements of the eyes, tongue, and neck?

A

corticobulbar

121
Q

where does the corticobulbar pathway descend from?

A

cerebral cortex along corticobulbar tract

122
Q

do all axons of the corticobulbar pathways cross over?

A

no

123
Q

why does the face have a large representation in the motor homunculus?

A

emotionally expressive

124
Q

what are the 4 actions of the basal nuclei?

A
  1. control initiation of movement
  2. control suppression of unwanted movement
  3. regulation of muscle tone
  4. regulation of non-motor processes
125
Q

in what way do basal nuclei control the suppression of unwanted movement?

A

tonic inhibition of neurons in the thalamus

126
Q

in what way do basal nuclei regulate muscle tone?

A

they send action potentials through the reticulospinal tract

127
Q

in what way do basal nuclei regulate non-motor processes?

A

limbic system

128
Q

what are 3 diseases of the basal nuclei?

A

parkinson’s, huntington’s, tourette’s

129
Q

what are the 4 roles of the cerebellum?

A
  1. monitors intention for movement
  2. monitors actual movement
  3. compares command signals with sensory information
  4. sends out corrective feedback
130
Q

does smooth muscle have myofibrils?

A

no

131
Q

what is unique about thick filaments in smooth muscle?

A

have myosin crossbridges alone entire length

132
Q

thin filaments of smooth muscle are composed of tropomyosin but no _____

A

troponin

133
Q

does smooth muscle have z lines?

A

no

134
Q

where do you find smooth muscle?

A

lining hollow structures and organs

135
Q

smooth muscle cytosolic calcium concentration are increased in a ____ _____

A

graded manner

136
Q

the amount of tension generated in a smooth muscle depends on what?

A

concentration of calcium in the cytosol

137
Q

in what 3 ways can extracellular calcium enter for smooth muscle contraction?

A

voltage calcium channels, ligated calcium channels, stretch activated cation of sodium and calcium

138
Q

what is the purpose of G-protein coupled receptors in smooth muscle contractions?

A

release of calcium from intracellular stores

139
Q

____ is the calcium sensor in smooth muscles

A

calmodulin

140
Q

how is kinase activated in smooth muscle?

A

ca bound calmodulin complex binds to myosin light-chain kinase

141
Q

what is the role of myosin light chain kinase (MLCK) in smooth muscle?

A

phosphorylates myosin’s regulatory light chain when active

142
Q

what activates the MLCK in smooth muscle?

A

ca calmodulin

143
Q

what is the role of myosin light chain phosphatase (MLCP)?

A

dephosphorylates myosin’s regulatory light chain to relax smooth muscle

144
Q

myosin is related to ___ filament

A

thick

145
Q

actin is related to ____ filament

A

thin

146
Q

activated MLCK phosphorylates the myosin regulatory light chain (RLC) by transferring a ______ from ____

A

phosphate, ATP

147
Q

contraction in smooth muscle is ____ and lasts ____ than contraction in skeletal muscle

A

slower, longer

148
Q

what two things lead to relaxation in smooth muscles?

A

decrease in sarcoplasm calcium levels, dephosphorization of myosin by MLCP

149
Q

___ ___ ___ ____ are connected by gap junctions so that excitation of cell results in the excitation of the entire collection of interconnected muscle cells

A

single-unit smooth muscles

150
Q

____ _____ ____ _____ are rare and activate individually after reception of the activation signal

A

muti-unit smooth muscles

151
Q

for both cell types of autonomic innervation, physical interconnections in the ______ of the cell membrane facilitate the development of tension through smooth muscle tissue

A

desmosomes

152
Q

the stomach has what type of autonomic innervation cell type?

A

single-unit

153
Q

the eye and uterus prior to pregnancy have what type of autonomic innervation cell type?

A

multi-unit

154
Q

pacemaker cells have an unsteady resting membrane due to ___ ___ ____

A

leaky ion channels

155
Q

in slow wave autorythmic cells, threshold is never reached and an ____ signal is needed to reach potential

A

autonomic

156
Q

the knee jerk reflex is a _____ _____ ____

A

monosynaptic reflex arch

157
Q

the knee jerk flex is a ___ lateral reflex

A

ipsi

158
Q

the ____ ____ ____ _reflex causes muscle relaxation in response to too much tension and regulates muscle tension

A

golgi tendon organ

159
Q

the golgi tendon organ reflex is ___lateral

A

ipsi

160
Q

in the golgi tendon organ reflex, the opposing muscle is activated/contracts through a _____ reflex

A

polysynaptic

161
Q

the withdrawal reflex (flexor reflex) involves ____ receptors

A

pain

162
Q

the withdrawal reflex (flexor reflex) is ___lateral

A

ipsi

163
Q

the withdrawal reflex (flexor reflex) is a ____ reflex arch to move a limb

A

polysynaptic

164
Q

the withdrawal reflex (crossed extensor reflex) causes what?

A

extension of the opposite limb during a flexor reflex to maintain balance

165
Q

the withdrawal reflex (crossed extensor reflex) is a _____ reflex arch

A

poly

166
Q

the withdrawal reflex (crossed extensor reflex) is ____lateral, as sensory inputs enter one side of the spinal cord and motor outputs exit on the opposite side

A

contra

167
Q

a ____ is a brief contraction by a muscle stimulated by a single action potential

A

twitch

168
Q

what are the 3 phases of twitch?

A

latent, contraction, relaxation

169
Q

the ___ phase is the brief delay between the situation and the start of contraction

A

latent

170
Q

the ____ phase is the time period when the muscle is actively generating tension

A

contraction

171
Q

the ____ phase is the time period when the muscle tension is decreased to baseline

A

relaxation

172
Q

multiple stimuli leads to a wavering but sustained contraction called ____ _____

A

incomplete/unfused tetanus

173
Q

a high frequency rate of stimuli makes the muscle not relax at all and a maximum force to be reached. This is ___ _____

A

complete tetanus

174
Q

large motor units control what type of movement?

A

large-scale and powerful

175
Q

small motor units control what type of movement?

A

precise

176
Q

____ stimulus activates a single motor unit and produces a small force contraction

A

threshold

177
Q

____ stimulus recruits and activates multiple motor units and produces a greater force

A

submaximal

178
Q

____ stimulus recruits and activates all motor neurons and produces maximum contraction force

A

maximal

179
Q

isometric contraction can occur when?

A

you try to lift an object too heavy for your muscles to move

180
Q

______ contractions are used to maintain posture

A

isometric

181
Q

in ____ contractions, tension develops in the muscle but does not reach the force level required to move the load

A

isometric

182
Q

in an ____ contraction, tension rises to a level larger than the load and remains contact while the muscle changes lnegth

A

isotonic

183
Q

____ contraction is the contraction used when moving objects

A

isotonic

184
Q

_____ is the major factor that determines the shortening velocity of a muscle

A

load

185
Q

in ___ contractions, load and velocity and inversely relation, and as load increases, shortening velocity decreases

A

isotonic

186
Q

tetanus is the maximum _______

A

tension

187
Q

maximum shortening velocity occurs with ___ load

A

zero

188
Q

maximum isometric tension occurs with ____ velocity

A

zero

189
Q

human muscle nerves are stimulated through skin at points known as ____ _____

A

motor points

190
Q

the duration of a muscle twitch is determined by what?

A

speed at which calcium is released into the sarcoplasm compared to the slower re-uptake of calcium into the SR by CA ATPase

191
Q

what leads to a larger stimulus in muscle contraction?

A

build up of calcium

192
Q

____ ___ _____ responds to changes in muscle length

A

muscle spindle reflex

193
Q

____ _____ ___ responds to tension changes

A

golgi tendon reflex

194
Q

____ is needed to allow myosin to release from actin

A

ATP

195
Q

the end plate potential is a ____ potential

A

graded

196
Q

is an isometric contraction, the latent period allows for what to occur?

A

build up of tension

197
Q

what is the Y axis on an isotonic graph?

A

distance shortened

198
Q

does smooth muscle have sarcomeres?

A

no

199
Q

what is unique about the calmodium calcium sensor in smooth muscles?

A

is not bound/is free in the cytoplasm

200
Q

in smooth muscle, the phosphate group is added to what chain on the myosin light chain?

A

regulatory

201
Q

what removes phosphate from myosin in smooth muscle?

A

phosphatase

202
Q

what is the overall goal of alpha/gamma coactivation?

A

resent in sensitivity to muscle spindle length changes

203
Q
A

Human Physiology (9 decks)

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