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22 Cards in this Set
- Front
- Back
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When is peripheral sensation appreciated? |
When it reaches the cerebral cortex |
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Describe a direct pathway |
3 neurons Somatotopically organised, serve a sensory discriminative function, Project to primary somato cortex on contralateral side |
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Describe indirect pathway |
Project more diffusely, multiple synapses in the CNS, poor somatotopy, serve an affective arousal function and project to limbic cortices |
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What is the assesment of direct pathways useful for? |
Diagnostically for localization of nervous system lesions |
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Where are cutaneous tactile receptors located? |
In glabrous and hairy skin |
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Describe cutaneous tactile repceptors |
Typically low-threshold mechanoreceptors and may be encapsulated or unencapsulated. Often accompanied by free nerve endings |
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What is a meissner and paccian corpuscles? |
Rapidly adapting and can detect transient stimuli such as motion |
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What are merkel cells? |
Slowly adapting and can detect skin displacement and duration |
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Hair follicle innervation? |
May be innervated by several differentaxons, allowing some discrimination of motion, its direction or orientation andvelocity. |
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What are nociceptors |
High threshold mechanonociceptors or poly nociceptors |
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What are deep tactile receptors |
Located in the dermis, fascia around muscles, and bone in the peridontium. Includes Pacinian corpuscles, Ruffini endings and other specialized encapsulated receptors |
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What do DTRs respond to? |
Pressure, vibration, stretch, distension or tooth displacement |
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What are proprioceptive receptors? |
Include muscle spindles and golgi tendon organs |
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Slide 6 |
Structure/Function summary |
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What forms the receptive field? |
formedby all of the receptors that can influence the activity of a single sensory(DRG) neuron. |
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How does the size of receptive fields vary? |
Varies with the area of the body, with very small receptors in the fingers and and larger on other body surfaces |
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What determines the discriminative ability of the area |
Size and number of the receptive fields |
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When considering receptive fields as non overlapping, what does activation yeild? |
Stimulus localization, modality and intensity information, depending upon the magnitude and type of stimulus |
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What does the sequential activation of receptive fields yield? |
Detection of motion, its velocity, and directio nor stimulus Only supply one modality or a limited amount or cross modality interpretation |
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What occurs with overlapping receptive fields? |
When an AP is generated in a sensory neuron the entire receptive field of several different receptors is activated |
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What can be obtained through the comparison of receptive field activation |
Greater degree of discriminative sensation Spinal cord and dorsal solumn nuclei are the first level of circuitry to process this type of information |
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Slide 11 Spinothalamic Tract |
and pathways |
