The Neuromuscular Junction - Medicine BM5 NLM1 0.0 / 5 ? MedicineMedicinePhysiologyNeuromuscular JunctionBiologyUniversityNone Created by: ex-LechiayimCreated on: 15-02-14 19:21 What is the NMJ? The point at which neuronal activity is transduced into movement 1 of 24 What provides the final output pathway from the spinal cord to the effector? Lower motor neuron 2 of 24 Select the most accurate statement regarding lower motor neurons. LMNs are myelinated & their cell body is in lamina IX of the spinal cord 3 of 24 Select the structure which can be found most posterior in the spinal cord. Dorsal horn 4 of 24 What type of matter is contained within the dorsal horn? Grey matter 5 of 24 What is another name for a LMN? Alpha motor neuron 6 of 24 What range of muscle fibres can one LMN innervate? 10-1000 muscle fibres 7 of 24 What is a motor unit? A group of muscle fibres innervated by a single motor neuron 8 of 24 At the NMJ there are multiple terminal boutons. What is a terminal boutons? The site of neurotransmitter release 9 of 24 Which two substances join to form ACh? Acetyl CoA & Choline 10 of 24 Through what mechanism is ACh released from the presynaptic membrane? Calcium-dependent exocytosis 11 of 24 Which enzyme rapidly hydrolyses ACh after it has caused signal transduction on the post-synaptic terminal? Acetylcholinesterase 12 of 24 What are the two products of the metabolism of ACh? Acetic Acid & Choline 13 of 24 What is an end-plate potential? Depolarization of the motor end plate 14 of 24 How many sub-units make up the nicotinic type II receptors? Three 15 of 24 Activation of the nicotinic type II receptors causes what? Opening of voltage-gated sodium channels 16 of 24 Where are the greatest potentials recorded? At the NMJ 17 of 24 True or false: depolarisations rapidly decline as your move further away from the NMJ? True 18 of 24 True or false: An action potential in the motor neuron will always result in a muscle contraction? True 19 of 24 True or false: a single AP will result in a single twitch? True 20 of 24 True or false: increasing the frequency of stimuli will result in summation of the EPP and increased tension in the muscle? True 21 of 24 True or false: Very high frequencies of stimuli will result in tetanus (smooth contraction resulting in generation of maximum tension)? True 22 of 24 Denervation is usually associated with what? Lesion of a lower motor neuron 23 of 24 What is denervation hypersensitivity? Redistribution of ACh receptors away from motor end plates causing reactivity to ACh along the length of the muscle fibre 24 of 24
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