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Med Neuro2 Lect2
Med Neuro Lect2 Peripheral Somatic Sensory
Question | Answer |
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3 Main types of somatosensory Information? | 1.Extroceptive (mechanoreceptors): sense touch, pressure, & vibration. 2.Proprioceptive (Kinesthesia): sense position & movement. 3.Interoceptive (nocioceptive): sense temperature & pain as well as tissue condition |
How does the degree of sensitivity of a region (ie the amount of sensory representation from that region) relate to that regions representation in the Cortex? | Directly correlated: The more senisitive an area is (the more sensory nerves, the less stimulation required to transmit a signal) the larger its representation is in the cortex. **Hands: large cortex, Calf: small cortex representation. |
How does the conduction velocity of type C fibers differ from that of type Aalpha and Abeta? | Aalpha & beta fibers are large, with uniform and quick conductions. **type C fibers are small, with non-uniform, prolonged conduction velocties. |
Which nerves provide us with Epicritic senses? What are their conduction speeds? Are they encapsulated? | BIG FIBERS: 1.Aalpha to skin & Group Ia & Ib to muscle (11-20um): 80-120ms conduction velocity. 2.Abeta to skin & Group II to muscle (6-12um): 35-75ms conduction velocity. **Aalpha & Abeta have encapuslated endings. |
Which nerves provide us with Protopathic senses? What are their conduction speeds? Are they encapsulated? | SMALL FIBERS: 1.Adelta fibers to skin or Group III to muscle (1-5um): 5-30ms conduction velocity. 2.C fibers to skin or Group IV to muscle (0.2-1.5um): 0.5-2ms conduction velocity. **NOT encapulated, have much higher treshold, reflexes are fast |
4 types of cutaneous touch corpuscles | 1.Pacinian corpusles. 2.Meissner’s corpusles. 3.Merkel’s discs. 4.Ruffini’s endings. |
Ruffini's: location, type of adaptation, type of sensation detected, size of receptive field? | 1.Location: Deep in Dermis. 2.Adaptation: Slow. 3.Sensation detected: Shape & size of displacement. 4.Receptive field: Large. |
Meisner's Corupuscle: location, type of adaptation, type of sensation detected, size of receptive field? | 1.Location: Superficial (b/w dermis & epidermis). 2.Adaptation: Rapid. 3.Sensation detected: Stimulus movement (low freq vibration). 4.Receptive field: Small. |
Pacinian Corpuscle: location, type of adaptation, type of sensation detected, size of receptive field? | 1.Location: Deepest in Dermis. 2.Adaptation: Rapid. 3.Sensation detected: Stimulus movement (high freq vibration). 4.Receptive field: Large |
Merkel's Disc: location, type of adaptation, type of sensation detected, size of receptive field? | 1.Location: Superficial (b/w dermis & epidermis). 2.Adaptation: Slow. 3.Sensation detected: Shape & size displacement. 4.Receptive field: Small. |
What determies how the cutaneous touch corpuscle will repsond to a stimuli? | The SHAPE of it's Capsule. **produce different signals depending on the shape. |
What is the mechanism behind the rapidly adapting corpuscles? | 1.Stimuli pressure compresses the capusle which causes large signal. 2.Steady state occurs if stimuli doesn't move, the capsulated nerve will stop sending signals. 3.When the stimulus pressure is removed from the capsule, nerve will fire again. |
When is the only time rapidly adapting corpuscles (pacinian & Meisner's) will send signals? | When the Capsule is CHANGING. **very good at telling movement & vibration) |
When is the only time slowly adapting corpuscles (Merkel's discs & Ruffini's endings) will send signals? | As long as the capsule is compressed/distorted. **very good at telling how far the stimulus is moving into the skin. |
Pacinian & Meisner's corpuscles are both rapid adapting, do they detect the same type of moving stimuli? | NO: 1.Pacinian movement stimuli: High frequency, low threshold/skin indentation. 2.Meisner's: Low frequency, high threshold/skin indentation. |
Why are small receptive fields advantageous? which corpuscles have small receptive fields? | MAPPING! The smaller the receptive fields, the better mapping we have to tell us EXACTLY where the stimulus is coming from. **Meisner's & Merkel's have small fields and are locted superficially. |
Somatotopy in the Dorsal Spinal Column (DSC), Spinocerebellar Tract (SCT), and Anterolateral System (ALS) | 1.DSC: Medial: Feet/Sacral, Lateral: Hands/cervical. 2.SCT: Medial: Hands/cervical, Lateral: Feet/sacral. 3.ALS: Medial: Hands/cervical, Lateral: Feet/Sacral. Medial: |