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MCDB 1B > Muscles > Flashcards

Muscles Flashcards

1
Q

What is required for muscle function

A

interaction of protein filaments

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2
Q

is muscular activity a related to the nervous system

A

yes it is a response to input from the nervous system

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3
Q

What composes the thin filaments

A

composed mainly of actin

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4
Q

what composes the thick filaments

A

composed mainly of myosin

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5
Q

what do muscle cell contractions rely on

A

interactions between thin and thick filaments

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6
Q

how do contractions occur

A

thick and thin filaments overlap which increases during the contraction, after contraction everything slides

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7
Q

what powers contractions

A

powered by ATP

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8
Q

what are the three types of muscles in vertebrates

A

skeletal, cardiac, and smooth

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9
Q

what does skeletal muscle control/ involve

A

voluntary movement and breathing

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10
Q

what does cardiac muscle control/ involve

A

beating of the heart

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11
Q

what does smooth muscle control/ involve

A

involuntary, movement of internal organs

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12
Q

what is the functional unit of a muscle called

A

a sarcomere

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13
Q

Does the I band consist of only actin, only myosin, or both.

A

The I band consists of only actin

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14
Q

Does the H zone consist of only actin, only myosin, or both.

A

The H zone consists of only myosin

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15
Q

how many actin surround a myosin filament

A

each myosin is surrounded by 6 actin

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16
Q

what is titan

A

it is the largest protein in the body (spans entire sarcomere)

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17
Q

what is the function of titan

A

titan holds myosin in place because the only thing myosin touches is the M band

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18
Q

why is skeletal muscle also called striated muscle

A

because the arrangement of the myofilaments create a pattern of light and dark bands

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19
Q

What is the structure of myosin

A

each myosin has a long ‘tail” and a globular “head”

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20
Q

what is the function of the myosin head

A

The myosin head binds to actin filaments and pull them towards the center of the sarcomere. muscle contractions require the repeated cycle of this

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21
Q

What are the regulatory proteins

A

Tropomyosin and troponin complex

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22
Q

what are the regulatory proteins

A

tropomyosin and the troponin complex are additional proteins that bind to actin strands on thin filaments

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23
Q

what is the purpose of the regulatory proteins

A

they prevent actin and myosin from interacting. for muscle contractions to occur, the myosin binding sites must be exposed

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24
Q

What do calcium ions do for muscle contractions

A

they bind to the troponin complex and expose the myosin binding sites

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25
Q

how are calcium ions and contractions related

A

contraction occurs when the concentration of Ca2+ is high; muscle contraction stops when the concentration of Ca2+ is low

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26
Q

what is the stimulus that leads to a muscle contraction

A

an action potential

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27
Q

where does the action potential occur

A

in a motor neuron that synapses with the muscle fiber

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28
Q

the neurotransmitter acetylcholine is released by the synaptic terminal what does it do

A

acetylcholine depolarizes the muscle, causing it to produce an action potential

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29
Q

how do action potentials travel inside the muscle fibers

A

action potentials travel to the interior of the muscle fibers along transverse (t) tubules

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30
Q

what do the action potentials cause to be released

A

the action potentials along T tubules cause the sarcoplasmic reticulum to release Ca2+

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31
Q

how does the calcium get out when the contraction is over

A

transport proteins in the SR pump calcium out of the cytosol

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32
Q

where is calcium released from

A

the sarcoplasmic reticulum

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33
Q

what does the calcium bind to

A

binds to troponin

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34
Q

where is the troponin that the calcium binds to

A

troponin in the actin filaments

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35
Q

what does calcium binding to troponin do to the cell

A

it leads to a conformational change in the tropomyosin

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36
Q

what does the conformational change in tropomyosin do

A

it allows actin-myosin interaction

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37
Q

contraction of the muscle is graded. what does this mean

A

the extent and strength of its contraction can be voluntarily altered

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38
Q

how does the nervous system produce the graded contractions

A

the number of fibers that contract and the rate the fibers are stimulated

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39
Q

how many muscle fibers can synapse with each motor neuron

A

multiple muscle fibers although each fiber is controlled by only one motor neuron

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40
Q

what is a motor unit

A

a single motor neuron and all the muscle fibers it controls

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41
Q

what is a twitch/ single twitch

A

when action potentials are close together in time; tension increases

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42
Q

what is tetanus

A

a state of sustained contraction produced when the rate of stimulation is so high that muscle fibers cannot relax between stimuli

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43
Q

what are the three systems for obtaining ATP

A

immediate system, glycolytic system, oxidative system

44
Q

what is the immediate system

A

it uses preformed ATP and creatine-phosphate

45
Q

how long does the immediate system last for

A

can only power muscles for 10 seconds or less

46
Q

where is the energy stored in the immediate system

A

it stores energy in phosphate bonds which is then transferred to ADP

47
Q

why does the immediate system get exhausted so fast

A

it gets exhausted within seconds because the muscle can only store very little creatine phosphate and it burns through it fast

48
Q

what is the glycolytic system

A

metabolizes carbohydrates to pyruvate and lactic acid

49
Q

how is the glycolytic system different from the immediate system

A

it makes ATP quickly available but doesn’t produce a lot of ATP

50
Q

how much ATP is produced from the glycolytic system

A

1 glucose = 2 ATP

51
Q

where does the glycolytic system occur

A

it occurs in the cytoplasm (sarcoplasm)

52
Q

is the glycolytic system anaerobic or aerobic

A

anaerobic it doesn’t need oxygen

53
Q

how long does the glycolytic system last for

A

provides energy for less than one minute

54
Q

why does the glycolytic system last for only a minute

A

lactic acid accumulates; muscle function decreases as it leads to acidosis

55
Q

what is the oxidative system

A

it metabolizes carbohydrates and fatty acids to h2o and co2

56
Q

why is the oxidative system efficient

A

it produces large amounts of ATP through oxidative phosphorylation; 1 glucose = 36 ATP

57
Q

is the oxidative system anaerobic or aerobic

A

aerobic it requires oxygen

58
Q

where does the oxidative system take place

A

it occurs in the mitochondria

59
Q

why is the oxidative system slower than the other two systems

A

ATP has to defuse from mitochondria to the myosin in the sarcoplasm

60
Q

what do oxidative fibers have

A

these fibers have many mitochondria, a rich blood supply, and a large amount of myoglobin

61
Q

what is myoglobin

A

a protein that bind oxygen more tightly than hemoglobin does. it has a higher affinity to oxygen that hemoglobin. red meat has a lot of myoglobin

62
Q

why is it important that oxidative fibers have a lot of myoglobin and a rich blood supply

A

oxidative fibers always need oxygen or else it will shut down

63
Q

why do glycolytic fibers tire easily

A

they cannot replenish ATP fast because they are using glycolysis as their primary source of ATP

64
Q

since glycolytic fibers tire so fast, what are they useful for

A

they are good for things that need a lot of power but fast; shot term work with maximum strength

65
Q

which fibers do fast twitches occur in

A

glycolytic fibers

66
Q

which fibers do slow twitches occur in

A

oxidative fibers

67
Q

what are fast twitches

A

enable brief, rapid, powerful contractions

68
Q

what are slow twitch fibers

A

contract more slowly but sustain longer contractions (much longer)

69
Q

do slow fibers have more or less sarcoplasmic reticulum than fast fibers

A

slow fibers have less than fast fibers

70
Q

do slow fibers pump Ca2+ fast or slow

A

slow fibers pump Ca2+ slowly

71
Q

do performance endurance athletes have more glycolytic or oxidative fibers

A

oxidative fibers. they have a higher proportion of slow twitch fibers than normal

72
Q

do sprinters have more glycolytic or oxidative fibers

A

glycolytic fibers. sprinters have a high proportion of fast twitch fibers than normal

73
Q

can you increase or decrease the amount of fast or slow twitch fibers you have to become a better athlete?

A

no you are born with it

74
Q

what does tropomyosin do

A

blocks myosin binding sites on actin

75
Q

what does troponin do

A

binds calcium

76
Q

what are transverse tubules

A

infoldings of the plasma membrane

77
Q

does the sarcoplasmic reticulum conduct action potentials in the interior of the muscle cells

A

no it stores calcium ions

78
Q

cardiac muscle consists of strained cells electrically connected by intercalated disks. what does this allow the cell to do

A

this allows depolarization to spread quickly

79
Q

can cardiac muscle generate their own action potentials without input from the nervous system

A

yes

80
Q

why are cardiac muscles branched and interdigitate

A

to allow them to withstand high pressures

81
Q

why do cardiac muscles have a lot of mitochondria

A

to continuously produce ATP, because if it doesn’t get ATP you are dead

82
Q

what is the junction between two muscle cells (intercalated discs) for

A

for connectivity for action potentials and strength

83
Q

what is the purpose of t-tubules and the SR in cardiac cells

A

allows the action potentials to spread quickly

84
Q

what does the pacemaker and conducting cells do

A

they initiate and coordinate heart contractions

85
Q

what initiates the action potentials in the cardiac muscles

A

the pacemaker

86
Q

if the pacemaker initials the action potentials, what does the conducting cell do

A

it spreads the action potentials quickly in order to synchronize contractions

87
Q

do contractions occur with or without input from the nervous system

A

without input from the nervous system

88
Q

the heartbeat is myogenic, what does this mean

A

it is generated by the heart muscle itself. the autonomic nervous system modifies the rate of pacemaker cells, but it is not necessary for their function.

89
Q

what do gap junctions do

A

they connect the cytoplasm of two neighboring cells

90
Q

what is the purpose of having gap junctions in the cardiac muscles

A

it allows direct electrical communication between cells

91
Q

why is having direct electrical communications important

A

it allows cardiac and smooth muscle cells to contract simultaneously

92
Q

why are cardiac and smooth muscle cells arranged in sheets

A

an action potential in once cell can spread to all others in the sheet

93
Q

where are smooth muscle cells found

A

found mainly in walls of hollow organs like circulatory, digestive and reproductive systems

94
Q

can smooth muscles contract on their own or must they have input from the nervous system

A

both. contractions may be generated by themselves because they can generate their own action potentials but they can slo be caused by stimulation from neurons

95
Q

why is smooth muscle not striated.

A

lacks striation because the actin and myosin are not regular arrayed

96
Q

a venom is injected by a wasp causes paralysis to voluntary muscles, while it doesn’t affect the myocardium. what is being targeted by the venom

A

the venom targets acetylcholine receptors

97
Q

which bands/zones shorten in the sarcomere when the muscle contracts

A

the I band and the H zone

98
Q

EDTA ius a calcium chelator (removes calcium from solution). what is a consequence for having calcium removed from sarcoplasm of muscle fibers

A

myosin and actin would not be able to bind to each other

99
Q

do fast twitch fibers fatigue slowly

A

no they fatigue quickly

100
Q

do slow twitch fibers fatigue slowly

A

yes

101
Q

does cardiac muscle have intercalated discs

A

yes

102
Q

what is a consequence for having a strong charged disbursed into the body

A

cross bridges form between actin and myosin

103
Q

you fluorescently tagged antibody that binds to actin. which parts of the sarcomere will show some of the fluorescence

A

The A and I bands will show the fluorescence.

104
Q

what is the I band

A

only actin

105
Q

what is the H zone

A

only myosin

106
Q

what is the A band

A

myosin and actin

107
Q

after the first 15 mins of a 10-km run, the major energy of the legs is supplied by what

A

oxidative metabolism

MCDB 1B (9 decks)

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