The Neuromuscular Junction - Medicine BM5 NLM1

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What is the NMJ?
The point at which neuronal activity is transduced into movement
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What provides the final output pathway from the spinal cord to the effector?
Lower motor neuron
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Select the most accurate statement regarding lower motor neurons.
LMNs are myelinated & their cell body is in lamina IX of the spinal cord
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Select the structure which can be found most posterior in the spinal cord.
Dorsal horn
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What type of matter is contained within the dorsal horn?
Grey matter
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What is another name for a LMN?
Alpha motor neuron
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What range of muscle fibres can one LMN innervate?
10-1000 muscle fibres
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What is a motor unit?
A group of muscle fibres innervated by a single motor neuron
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At the NMJ there are multiple terminal boutons. What is a terminal boutons?
The site of neurotransmitter release
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Which two substances join to form ACh?
Acetyl CoA & Choline
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Through what mechanism is ACh released from the presynaptic membrane?
Calcium-dependent exocytosis
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Which enzyme rapidly hydrolyses ACh after it has caused signal transduction on the post-synaptic terminal?
Acetylcholinesterase
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What are the two products of the metabolism of ACh?
Acetic Acid & Choline
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What is an end-plate potential?
Depolarization of the motor end plate
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How many sub-units make up the nicotinic type II receptors?
Three
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Activation of the nicotinic type II receptors causes what?
Opening of voltage-gated sodium channels
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Where are the greatest potentials recorded?
At the NMJ
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True or false: depolarisations rapidly decline as your move further away from the NMJ?
True
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True or false: An action potential in the motor neuron will always result in a muscle contraction?
True
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True or false: a single AP will result in a single twitch?
True
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True or false: increasing the frequency of stimuli will result in summation of the EPP and increased tension in the muscle?
True
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True or false: Very high frequencies of stimuli will result in tetanus (smooth contraction resulting in generation of maximum tension)?
True
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Denervation is usually associated with what?
Lesion of a lower motor neuron
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What is denervation hypersensitivity?
Redistribution of ACh receptors away from motor end plates causing reactivity to ACh along the length of the muscle fibre
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Other cards in this set

Card 2

Front

What provides the final output pathway from the spinal cord to the effector?

Back

Lower motor neuron

Card 3

Front

Select the most accurate statement regarding lower motor neurons.

Back

Preview of the front of card 3

Card 4

Front

Select the structure which can be found most posterior in the spinal cord.

Back

Preview of the front of card 4

Card 5

Front

What type of matter is contained within the dorsal horn?

Back

Preview of the front of card 5
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