Motor unit and skeletal muscle contraction Flashcards

1
Q

When is the only time a skeletal muscle will contract?

A

When it is stimulated by an electrical impulse by an electrical impulse from the CNS that exceeds the all or none threshold

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2
Q

What are motor neurones?

A

Specialised cells that rapidly transmit nerve impulses to a group of muscle fibres

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3
Q

Describe the features of a motor neurone

A

A cell body located in the brain or spinal cord with an extending axon that connects motor end plates to a group of muscle fibres

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4
Q

What does the motor unit consist of?

A

The motor neurone and its corresponding muscle fibres

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5
Q

What is resting potential?

A

The electrical difference between the inside of the axon (negative charge) and its surroundings (positive)

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6
Q

How is resting potential affected by an activated nerve?

A

A sudden change in voltage as sodium ions diffuse into the axon which triggers a wave of action potential that travels from the cell body down the axon to the synapse

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7
Q

What is action potential?

A

A positive electrical charge inside the nerve and muscle cells that conduct the nerve impulse down the neurone to the muscle fibre

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8
Q

What does the electromechanical process of sending a nerve impulse to the muscle fibres rely on?

A

A nerve’s action potential to conduct the nerve impulse as a wave of electrical charge through the axon to the nerve plates

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9
Q

What is a neurotransmitter?

A

A chemical produced and secreted by a neurone which transmits the nerve impulse across the synaptic cleft to the muscle fibre

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10
Q

What chemical is produced by the neurotransmitter?

A

Acetylcholine

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11
Q

What is the all or none law?

A

Complete or no muscular contraction depending on if the stimuli is above the threshold

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12
Q

What is the neuromuscular junction?

A

Where the axon’s motor end plates meet the muscle fibre

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13
Q

What is the synaptic cleft?

A

The small gap between the motor end plates and muscle fibre

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14
Q

What is the function of acetylcholine?

A

It is secreted into the synaptic cleft to aid the creation of muscle action potential if the electrical charge is above a threshold

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15
Q

Nerve impulse initiated in the (1) > impulse travels (2) by (3) to the synaptic cleft > (4) is secreted > muscle fibres contract if (5)

A
1 - motor neurone cell body 
2 - down the axon 
3 - action potential 
4 - acetylcholine 
5 - if the charge is above a threshold
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