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27 Cards in this Set
- Front
- Back
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Which sensory receptors have free nerve endings?
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nociceptors and thermoceptors
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quality of stimulus
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where it is, what it represents
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Four types of encapsulated mechanoreceptors
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1. Meissner's corpuscle
2. Pacinian Corpuscles 3. Merkel's Disks 4. Ruffini's corpuscles |
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Low threshold mechanoreceptors
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high sensitivity. weak stim causes them to fire APs. Innervated by large myelinated axons (type AB fast)
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Meissner's corpuscle
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fast adapting, small receptive fields
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Pacinian Corpuscles
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fast adapting, large receptive fields
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Merkel's disks
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slow adapting, small receptive fields
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Ruffini's corpuscles
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slow adapting, large receptive fields
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Where are all the nuclei or sensory axons located?
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in the dorsal root ganglion
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dorsal-column medial lemniscus pathway
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used by mechanoreceptors and proprioception receptors
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spinothalamic (anterolateral) pathway
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used by pain and temperature to ascend to the brain
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pathway of sensory information
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enter dorsal root ganglion in spinal cord, go up dorsal column ipsilaterally and terminate in the gracile or cuneate nuclei in the medulla
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gracile tract
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information from lower limbs
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Cuneate tract
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information from upper limbs, trunk and neck
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where are the gracile and cuneate nuclei located?
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in the caudal (posterior) medulla
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from medulla, pathway of sensory information
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medulla-->sensory portion of thalamus (VPL)--> cortex
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Ventral posterior lateral nucleus
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sensory portion of the thalamus
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Trigeminal tract
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infro trom the face. enters brainstem via trigeminal nerve at pons and terminates in the trigeminal brainstem complex. Crosses midline at pons, ascends to thalamus
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trigeminal brainstem complex
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two main components, principal nucleus (mechanosensory stimuli) and spinal nucleus (pain and temperature)
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VPL (Ventral posterior lateral nucleus)
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receives projections from the medial lemniscus carrying all somatic sensory info from body
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VPM (ventral posterior medial nucleus)
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receives axons from the trigeminal info from the face
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VPC
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ventral posterior complex, complete representation of the body
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All axons from the ventral posterior complex project where?
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layer IV of the somatosensory cortex
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Broadmann's area 3b and 1
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cutaneous stimuli (from the skin)
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Broadmann's area 3a
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proprioceptor stimuli
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Broadmann's area 2
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tactile and proprioceptive stimuli
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Secondary somatic sensory area
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receives info from all 4 SI areas and sends it to amygdala and hippocampus
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