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sciences > muscle > Flashcards

muscle Flashcards

1
Q

Skeletal and cardiac muscle appears

A

striated

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2
Q

Cardiac and smooth muscle is innervated by

A

autonomic NS

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3
Q

Smooth muscle lines the

A

hollow walls of organs

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4
Q

smooth muscle is responsible for

A

GI motility
constriction of blood vessels
uterine contractions

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5
Q

somatic neurons stimulate

A

skeletal muscle

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6
Q

Tendons

A

muscle attached to bones

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7
Q

tendons are composed of

A

strong connective issue which contains primarily collagen

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8
Q

muscle contracts: the ______ is brought closer to the _____

A

insertion point is brought closer to the origin

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9
Q

skeletal muscle is composed of muscle &

A

connective tissue

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10
Q

what is the function of connective tissue in skeletal muscle

A

Connective Tissue (CT) holds the contractile tissue together in bundles called fasicles to allow flexibility

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11
Q

Muscle fiber is a

A

single skeletal muscle cell

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12
Q

Skeletal muscle cells are

A

multinucleated synctia formed by the fusion of individual cells during development

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13
Q

skeletal muscle cells are innervated by

A

a single nerve ending

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14
Q

all skeletal muscle cells are innervated by ____ motor neurons

A

all skeletal muscle cells are innervated by __somatic__ motor neurons

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15
Q

Somatic motor neurons release _______ @ NMJ

A

ACh

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16
Q

the difference in regulation is the ______ of the signal

A

the difference in regulation is the timing of the signal

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17
Q

Sacrolemma is the

A

myofiber cell membrane

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18
Q

the sacrolemma differs from the Plasma membrane in that

A

it has an additional layer of polysaccharide & collagen

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19
Q

sacrolemma’s additional layer helps

A

fuse with the tendon fibers

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20
Q

myofibrils are units within each

A

myofiber

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21
Q

myofibrils in the muscle cell is like a specialized

A

organelle

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22
Q

myofibril is responsible for the

A

striated appearance of a muscle cell

the contractile force

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23
Q

what proteins are responsible for generation of muscle contraction in the myofibril

A

actin and myosin

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24
Q

actin

A

thin filaments

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25
Q

myosin

A

thick filaments

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26
Q

striated appearance of skeletal muscle is due to

A

overlapping arrangement of bands of thick and thin filaments in sacromeres

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27
Q

myofibril composition of sacromeres is

A

myofibril is composed of many sacromeres aligned end-to-end

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28
Q

each sacromere is bound by 2

A

z lines

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29
Q

thin filaments attach to ____

thin filaments ___ with thick filaments in the middle of the sacromere

A

z lines

overlap with thick filaments

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30
Q

thick filaments are _____ to z lines

A

NOT ATTACHED

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31
Q

I bands contain only

A

thin filaments

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32
Q

A bands

A

full length of thick

includes overlapping region

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33
Q

H zone

A

only thick

seen in resting sacromere

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34
Q

Mnemonic

Z line

A

Z line denotes boundarieZ of Sacromere

35
Q

Mnemonic

M line

A

M line in the Middle

36
Q

Mnemonic

H is

A

H is thick so thick filaments

37
Q

Mnemonic

I is

A

I is thin so thin filaments

38
Q

Mnemonic

A is

A

A is thick And thin

39
Q

Mnemonic to help remember the order

A

“Zee Intelligent Animal Has Muscle”
Z-I-A-H-M-H-A-I-Z
M is symmetry point

40
Q

contraction occurs when

A

thick and thin slide across each other

41
Q

contraction _____ z lines ____ to each other —> ____ length of muscle cell

A

contraction draws z lines close to each other —> shortening length of muscle cell

42
Q

where does the energy for filament sliding come from

A

ATP hydrolysis

43
Q

which enzyme uses ATP hydrolysis

A

myosin uses ATP hydrolysis to generate movement

44
Q

a myosin monomer is composed of a

A

head and a tail

45
Q

myosin head attaches to _____ when attached it is referred to as ______

A

specific site on actin - myosin binding site

when attached it is referred to as cross bridge

46
Q

filament sliding

A
  1. cross bridge formation
  2. power stroke
  3. release of actin
  4. ATP hydrolysis
47
Q

power stroke

A

myosin head moves to lower E. conformation –> pulls actin toward center of sacromere —> release of ADP

48
Q

each step of filament sliding theory and what is bound to myosin

A
  1. myosin binds to actin. Has ADP + Pi
  2. myosin bound to actin. releases ADP.
  3. ATP binds to myosin. myosin releases actin
  4. ATP hydrolysis –> myosin head to cock into high energy conformation
49
Q

ATP is required for

A

myosin to release actin

50
Q

when does myosin hydrolyze ATP

A

when it is not bound to actin and to move it forward into the high energy conformation

51
Q

in a myofiber contraction only occurs when cytoplasmic concentration of

A

calcium increases

52
Q

thick filaments

A

contain tropoin-tropomyosin complex

53
Q

when no Calcium is present

A

tropoin-tropomyosin complex prevents

54
Q

tropomyosin

A

blocks all myosin binding sites
long fibrous proteins
winds along actin polymer

55
Q

tropoin

A

calcium binds to tropoin
globular protein
bound to tropomyosin

56
Q

calcium binds to ______ –> _________ change

A

calcium binds to tropoin –> conformational change

57
Q

conformational change results in __________

A

conformational change causes tropomyosin to move out of the way

58
Q

in summary binding of calcium to ______ causes _____ change which results in ______ moving and allowing for _________ to attach to _____ resulting in the ______.

A

in summary binding of calcium to tropoin causes conformational change change which results in tropomyosin moving and allowing for myosin head to attach to actin resulting in the filament_sliding.

59
Q

NMJ is synapse between axon and ______.

NMJ structure is a ______

A

myofiber
the structure is a long trough/invagination (infolding)
NOT a single point

60
Q

What is the purpose of the NMJ being a long trough?

A

the purpose is to allow neuron to depolarize a large region of the postsynaptic membrane at once

61
Q

postsynaptic membrane is the _______

A

motor end plate (myofiber cell membrane)

62
Q

What neurotransmitter is released at the NMJ?

A

ACh

63
Q

chemical synapse

A

AP arrives @ axon –> triggers opening of Volt. Gated Calcium channels –> increase in calcium in the cell —> release of ACh

64
Q

post synaptic membrane has ___ receptors which are _______ channels

A

post synaptic membrane has ACh receptors which are _ligand gated sodium _ channels

65
Q

since the myofiber is very thick AP on its surface will not depolarize the interior. Thus the solution was to

A

have deep invaginations of cell membrane –> allow AP to travel to thick of cell

66
Q

what are the deep invaginations of the myofiber membrane called?

A

T tubules

67
Q

Sacroplasmic reticulum

A

specialized membrane in myofiber

specialized smooth endoplasmic reticulum

68
Q

Sacroplasmic reticulum contains _____ channels

A

Sacroplasmic reticulum contains V.G. Calcium channels –> allow Calcium to rush out of the S.R. into the sacroplasm

69
Q

NS can force increase in contraction by 2 means which are

A
  1. motor unit recruitment

2. frequency summation

70
Q

describe

1. motor unit recruitment

A
  1. motor unit recruitment group of myofibrils innervated by single motor neuron’s axon
71
Q

describe

2. frequency summation

A
  1. frequency summation - if insufficient time for the calicum to be sequesterd by the SR then 2nd contraction builds on the first
72
Q

for f. summation to occur the amount of time must be greater than the ________ but also less than the time for _______

A

for f. summation to occur the amount of time must be greater than the ___refractory period___ but also less than the time for __calcium to return to low resting potential___

73
Q

muscles have a lot of what organelle

A

highly aerobic with lots of mitochondria

74
Q

myoglobin

A

Role is an O2 reserve (takes O2 from Hemoglobin and releases it as needed)
similar to 1 subunit of Hemoglobin
globular protein

75
Q

prolonged contraction leads to

A

anaerobic respiration –> lactic acid –> blood –> decrease in pH —> picked up by the liver —> pyruvate

76
Q

anaerobic respiration –> _____ –> blood –> _____ in pH —> picked up by the ____ —> _____

A

anaerobic respiration –> lactic acid –> blood –> decrease in pH —> picked up by the liver —> pyruvate

77
Q

Differences between cardiac versus skeletal muscle

A
  1. SYNCYTIUM
    - Smooth muslce is a STRUCTURAL syncytium (fusion of individual muscle cells forming multinucleated cell)
    - Cardiac is a FUNCTIONAL syncytium (cardiac cells are connected by intercalated discs)
  2. Cardiac muscle cells are each connected to several neighbors by intercalated disks
  3. Cardiac muscle contraction does NOT depend on stimulation by motor neurons
    - ACh is inhibitory
  4. AP in cardiac muscle depends on BOTH voltage-gated sodium channels (fast channels) AND on voltage-gated calcium channels (slow channels)
78
Q

function of intercalated disk

A

gap junctions
which allow AP propagation throughout the entire heart without allowing nuclei and cytoplasmic contents to be shared (only small ions can pass)

79
Q

Similarities between cardiac versus skeletal muscle

A
  1. both are striated
  2. thick and thin filaments organized into sacromeres.
  3. T tubules
  4. tropoin-tropomyosin regulated contraction in the same way
  5. length-tension relationship is the same though MORE significant in CARDIAC.
80
Q

structural syncytium

A

is a multinucleated cell that results from multiple cell fusions of uninuclear cells

81
Q

Similarities between smooth and skeletal muscle

A
  1. contraction accomplished by actin & mysoin filament sliding
  2. 4 step contracile cycle
  3. contraction triggered by increase in calcium
  4. Do not branch
82
Q

Differences between smooth and skeletal muscle

A
  1. Narrower & shorter
  2. No T tubules
  3. only 1 nucleus / cell. connected to neighbors by gap junctions. FUNCTIONAL syncytia
  4. thick and thin NOT organized into SACROMERES. DISPERSED in cytoplasm
  5. Tropoin-tropomyosin NOT present. Contraction is regulated by CALMODULIN (binds to Ca) myosin light chain kinase (MLCK)
  6. Smooth muscle SR poorly developed. cell relies heavily on extracellular calcium
  7. AP varies based on location on smooth muscle (some have no sodium channels)
  8. Smooth muscle must sustain longer contractions. AP similar to cardiac
  9. Smooth muscle has fluctuating resting potential - “slow waves”
  10. innervated by motor neurons bur are autonomic motor neurons
83
Q

calmodulin myosin light chain kinase (MLCK):

Calcium binds to _______ –> activates _____ –> ______ myosin –> _____ myosin

A

Calcium binds to _calmodulin__ –> __activates MLCK__ –> __phosphorylates__ myosin –> __activated__ myosin

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