A sksletal muscle can only contract when stimulted by an electrical impulse sent from the Central Nervous System.
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What are motor neurons?
A nerve cell which conducts a nerve impulse to a group of muscle fibres.
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What is a motor unit and what is its function?
A motor neuron and the muscle fibres stimulated by its axon. It functions to carry nerve impulses from the brain and spinal cord to the muscle fibres, initiating muscular contraction.
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What is an action potential?
Positive electrical charge inside the nerve and muscle cells which conducts the nerve impulse down the neuron and into the muscle fibre.
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What is the neuromuscular junction?
The point where the axon's motor end plates meet the muscle fibre.
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What is the synaptic cleft?
A small gap between the motor end plates and muscle fibre.
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What is a neurotransmitter?
A chemical is produced and secreted by a neuron which transmits the nerve impulse across the synaptic cleft to the muscle fibre.
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What is the 'all or none' law?
Depending on wheter the stimulus is above a threshold, all muscle fibres will give a complete contracion or no contraction at all.
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First Stage of a Motor Unit
Nerve impulse initiated in the motor neuron cell body.
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Second Stage of a Motor Unit
Nerve impulse conducted down the axon of the motor neuron by a nerve action potential to the synaptic cleft.
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Third Stage of a Motor Unit
Neurotransmitter called acetylcholine is secreted into the synaptic cleft to conduct the nerve impulse across the gap.
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Fourth Stage of a Motor Unit
If the electrical charge is above a threshold, the muscle fibre will contract.
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Fifth Stage of a Motor Unit
This happens in an 'all or none' fashion.
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Other cards in this set
Card 2
Front
Skeletal Muscle Contraction
Back
A sksletal muscle can only contract when stimulted by an electrical impulse sent from the Central Nervous System.
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