the neuromuscular junction Flashcards

1
Q

what does nerve signal trigger?

A

triggers muscle action potential

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2
Q

how does the neuromuscular interaction work?

A

delivered by one motor neuron

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3
Q

if a neuron is triggered how many fibres are triggered

A

1+ at the same time

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4
Q

what is a neuronal ending to a muscle fibre

A

neuromuscular junction

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5
Q

what do synaptic end bulbs do?

A

release neurotransmitter

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6
Q

how many steps is there at neuromuscular junction

A

4

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7
Q

what are the 4 steps in neuromuscular junction

A

-Release of the neurotransmitter, acetylcholine (ACh)
Diffuses across cleft
-Activation of ACh receptors on sarcolemma
-Generation of Muscle Action Potential
Repeats with each nerve action potential
-Breakdown of ACh by the enzyme acetylcholinesterase

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8
Q

what happens when a muscle initiates a contraction

A

Muscle action potential
Ca2+ released from the Sarcoplasmic
Reticulum (SR)
4 Ca2+ bind to troponin
Moves tropomyosin off actin sites
Myosin binds to actin and starts the contraction cycle

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9
Q

what does myosin bind to in the contraction cycle
what does it release

A

binding to actin
releases phosphate group
(forming cross-bridge)

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10
Q

what does the cross-bridge release in contraction cycle

A

ADP & shortening sarcomere (power stroke)

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11
Q

what does ATP bind to in and then release contracting cycle

A

binds to myosin
release of myosin from actin

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12
Q

if ATP is broken down to ADP & Pi what does it activate

A

myosin head to bind and start again

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13
Q

when the muscle is relaxing what happens

A

A breakdown of ACh happens
stops muscle action potentials by acetylcholinesterase

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14
Q

where do the Ca2+ ions go in relaxation in the muscles

A

transported back into SR lowering concentration

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15
Q

what happens when the nerves are cut in the muscle

A

fibres become flaccid
very limp

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