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MSK Biweekly Exam 1 > Taylor NMJ Excitation and Contraction > Flashcards

Taylor NMJ Excitation and Contraction Flashcards

1
Q

what is absolutely needed for a muscle contraction

A

calcium

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2
Q

motor neuron that innervates muscle

A

alpha motor neuron

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3
Q

a specific muscle fiber is only innervated by what

A

a specific motor neuron

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4
Q

1 alpha motor neuron and all of its fibers it innervates

A

motor unit

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5
Q

what increases surface area on muscle

A

post junctional folds

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6
Q

action potential down motor neuron causes what to open

A

voltage gated calcium channels (p or q)

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7
Q

what allows vesicle to fuse with membrane and Ach to be released

A

calcium binding to synaptotagmin and then causing conformational change where SNARE complex binds to membrane

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8
Q

parts of the SNARE complex

A

SNAP 25, synaptobrevin, and syntaxin

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9
Q

what receptor on postjunctional side acts as ligand gated ion channel

A

nicotinic Ach receptor

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10
Q

what happens after Ach binds its receptor

A

Na comes in and depolarizes membrane and if enough potential, will cause contraction

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11
Q

Ach is released in discrete packages called

A

quanta

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12
Q

how many quanta of Ach need to be released to cause contraction

A

50-300

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13
Q

type of channel that allows sodium to come through and depolarization to happen

A

fast voltage gated Na channel

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14
Q

Z line is made of this and it borders each sarcomere

A

alpha actinin

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15
Q

head of myosin filament has what binding sites

A

actin and ATP and light chain

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16
Q

what allows uncovering of myosin binding site on actin filament in resting state

A

when calcium binds troponin C

17
Q

6 steps of cross-bridge cycling for contraction

A
  1. myosin is bound to actin
  2. ATP binds myosin and detaches from actin
  3. ATP hydrolyzed to ADP and inorganic P
  4. Ca2+ binds troponin C and myosin is able to bind actin
  5. inorganic P is released and powerstroke happens
  6. ADP released and myosin remains attached to actin until ATP binds myosin
18
Q

what surrounds myofibril

A

sarcoplasmic reticulum

18
Q

what stores Ca2+ around myofibril

A

cisternae of sarcoplasmic reticulum

18
Q

DHPR and RyR allow calcium to leave sarcoplasmic reticulum and enter where

A

cytosol

19
Q

triad:

A

2 cisternae and 1 T-tubule

20
Q

Ach goes into T tubule and allows depolarization to happen opening what channels

A

L-type voltage gated calcium channel (DHPR) and ryanodine receptor (RyR)

21
Q

when Ca2+ is in cytosol, what can happen

A

it binds troponin C and allows myosin to bind actin so contraction can happen

22
Q

what pumps calcium back into sarcoplasmic reticulum

A

SERCA

23
Q

what protein keeps calcium in sarcoplasmic reticulum

A

Calsequestrin

24
Q

what degrades Ach so you don’t have constant contraction

A

Ach-ase

MSK Biweekly Exam 1 (11 decks)

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