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25 Cards in this Set
- Front
- Back
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What produces post synaptic potentials?
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Transmitter gated ion channels
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What do stimulus gated channels produce?
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Generator potentials (heat, stretch, chemicals)
Sensory transduction |
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What is transduction?
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The convergence of a stimulus into an electric signal
The bigger the generator potentials, the more action potentials produced Above theshold= AP |
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What determines receptive field size?
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Type of sensory neuron and position in the body
Smaller fields for touch discrimination |
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What are the 5 different ways primary afferents are classified?
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1. By sensory modality
2. By whether they monitor external effects or stimuli intrinsic to the body 3. By action potential conduction velocity 4. Whether they adapt rapidly to a stimulus or slowly 5. Naked endings/ encapsulated endings |
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What kind of sensory modalities are associated with naked endings?
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Pain, temp, itch
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What detects sustained pressure - detailed texture and shape?
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Merkel's endings (finger pads)
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What do Meissner's endings detect?
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Touch- brief response
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What detects vibration?
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Pacinian corpuscle (rapidly adapting)
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What detects sheer stress?
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Ruffini endings
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Why does conduction velocity fail and how is it measured?
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When nerves are compressed or damaged
Nerve conduction velocity test (determines site of compression) |
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Give an example of a slowly adapting afferent
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Merkle's disc
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Monitoring how rapidly a nerve ending adapts is good for measuring what?
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Static stimuli
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What does encapsulation do?
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Modifies the response
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What speed do C fibres travel and what do they detect?
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0.5-2m/s
Pain temp and itch |
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What speed to A delta fibres travel and what do they detect?
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5-30m/s
Pain temp |
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What speed to A beta fibres travel and what do they detect?
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35-75m/s
Skin, mechanoreceptors |
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What speed to A alpha fibres travel and what do they detect?
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80-120m/s
Muscle proprioceptors |
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What is the spinal cord divided into?
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Laminae I-IX
Different types of sensory neuron end in different laminae |
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What do laminae 1 and the outer of laminae 2 make?
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Substantia gelatinosa
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Where do A beta mechanoreceptors end?
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Laminae 2-5
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Where do A alpha muscle spindle sensory neurons end?
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Extend into the ventral horn (9)
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What is another name for a hemicord lesion?
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Brown- sequard lesion
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What causes posterior cord syndrome?
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Traumatic injury/ compression
Posterior spinal artery damage Multiple sclerosis Vit B12 deficiency Tabes dorsalis (tertiary syphilis) MOTOR PATHWAYS NOT AFFECTED |
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What are the symptoms of posterior cord syndrome?
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Clumbsiness due to impaired proprioception but good muscle strength
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