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53 Cards in this Set
- Front
- Back
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Where is glabrous skin found?
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Soles, palms (non-hairy skin)
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Golgi Tendon Organs VS Muscle Spindles
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Golgi Tendon: detect force exerted by muscle
Spindles: detect muscle stretch |
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What is the only ENCAPSULATED somatoreceptor?
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Mechanoreceptors (detect mechanical deformation)
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Where are the soma of somatoreceptors located?
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DRG
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A-alpha fibers
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Big, fast; proprioceptors
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A-beta fibers
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Big and fast; mechanoreceptors
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A-delta fibers
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Small and slow; pain, temp
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C fibers
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Small and slow; temp, pain, itch
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How does axon size affect susceptibility to anesthesia?
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Smaller fibers = most vulnerable
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How does stimulus intensity affect number of receptors activated?
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More intense stimuli activate more receptors
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How does intensity of a stimulus affect frequency of AP's fired?
What if the stimulus is constant? |
Higher intensity --> higher frequency AP firing
Eventually get accomodation |
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What is epicritic touch? Path taken?
Fibers utilized? |
Discriminative touch (touch, vibration, 2 point discrim, proprioception)
Dorsal Column Medial Lemniscal PW Large Fibers (A-alpha, A-beta, A-delta) |
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What is protopathic touch? Path taken?
Fibers utilized? |
Protopathic touch = pain (temp, some touch)
Utilized A-delta, C fibers Use Anterolateral PW |
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What disease can demonstrate proof of dermatomes?
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Shingles!
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Compare differences in first-order and second-order neurons in the Anterolateral and Dorsal Column Systems.
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Dorsal Column:
First order neuron synapses at spinomed jn Decussates Seond-order travels through Medial Lemniscus to thal, cortex Anterolateral: First order neuron synapses at spinal level Second order neuron spans (decussates) ant white commissure Goes up to thal then cortex |
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The dorsal column is divided into two segments. What are they and how do they differ in terms of information carried?
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Gracilis (medial): epicritic info from legs
Cuneatus (lateral): epicritic info from arms |
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What types of sensation would be affected in a spinal hemisection?
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(Brown-Sequard Syndrome)
Ipsilateral loss of touch Contralateral loss of pain (and paralysis on lesioned side) EXAMPLE OF DISSOCIATED SENSORY LOSS |
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What do the internal arcuate fibers connect?
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Nucleus Cuneatus (arms!) to Medial Lemniscus
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Where is the medial lemniscus located? How does info carried differ by region?
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Medial Lemniscus is above pyramids (centrally placed) at spinomedullary jn
Dorsal: arms (internal arcuate from nuc cuneatus) Ventral: legs (internal arcuate from nuc gracilis) |
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VPM: location, info carried
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intrathalamic nucleus; face (Ventral posteromedial nucleus)
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VPL: location, info carried
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Intrathalamic nucleus; leg info
Ventral posterolateral nucleus |
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S1: info received
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Localized, sharp, fast pain
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S2: info received
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lots of branching, poorly-localized, dull, aching, slow pain
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What nerves provide sensation to the head? Which regions?
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Trigeminal:
V1: nose to forehead V2: Upper lip to temples V3: Chin to loer temple C2: beack of head |
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Describe the epicritic pathway of the trigeminal nerve (in regard to facial sensation).
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A-beta fibers synapse on trigeminal ganglion
-->Main Sensory Nuc of V (pons) Second-order DECUSSATE go to VPM thal |
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Describe the protopathic pathway of the trigeminal nerve (with regard to facial sensation).
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Trigeminal Ganglion: A-delta, C fibers fire (many branches!!)on Spinal tract of V
Second-order decussate Travel to VP nuc in thalamus (and retricular formations) |
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Why does a person blink in both eyes when touched in one eye? Provide a mechanism.
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Corneal/Blink Reflex:
Touch eye-->CN V-->Main Sens Nuc of V -->VII L & R-->orbicularis oculi L & R |
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What are the symptoms of lateral medullary syndrome?
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Lateral Medullary Syndrome AKA WALLENBERG'S SYNDROME
due to occlusion of PICA results in loss of pain/temp in ipsi/contra face contra body |
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How does receptive field size differ with how superficial/deep a receptor is?
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Superficial receptors have SMALL receptive fields
Deep receptors have LARGE receptive fields |
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What are slow adapting receptors good at sensing? Fast adapters?
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Slow adapting: sense pressure, shape
Fast adapting: sense flutter and vibration |
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What regions of the body have highest two-point discrimination? Lowest?
How can this resolution be overlapped? |
Index finger/thumb/lip HIGH resoln; back lowest two point discrim
Increase resoln by: 1) overlapping receptive fields (decrease receptive field size) 2) Increase receptor density |
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What effect would a stroke to the somatosensory cortex have on sensation?
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Decreased two point discrimination (but no loss of general sensation)
It's just harder to discriminate/interpret stimuli |
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What effect would a disruption of epicritic sensation have on motor function?
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Impaired motor ability (coordination)
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Agnosia
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inability to recognize objects even with intact sensory
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Stereognosis
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3-D perception from skin/posn
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Astereognosis
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Inability or deficit in 3-d perception from skin/posn
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Apraxia
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Inabvility to perform skilled actions without sensory/motor deficits
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After reaching the sensory strip, where does sensory info head?
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Posterior Parietal Cortex
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What is hemineglect syndrome? Cause?
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deny limb or side of world; parietal lobe lesion/stroke
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Pain vs Nociception
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Pain is a PERCEPT of a stimulus
Nociception is the detection of damaged tissue (A-delta III, C IV fibers) |
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What fibers carry fast pain? Slow pain?
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Fast pain: A-delta
Slow pain: C fibers (dull, aching pain) |
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Mechanical Receptor vs Polymodal Receptor
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Mech: intense pressure or damage (A-delta)
Polymodal: high intensity mechanical, chemical, or thermal stimulus (C fibers); SENSITIVE TO HISTAMINE (itch) |
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How is paradoxical cold achieved?
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Cold and Warm receptors have some overlap (something warm can feel cold!)
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Explain 'pain can gain'
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Sensitization of receptors with repeated stimulus (harlmess stimulus becomes noxious; e.g., water torture)
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Allodynia
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painful response to non-noxious stimulus (central mech)
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Hyperalgesia: primary and secondary
Include central/peripheral mechs |
Hyperalgesia: excessively painful response to noxious stimulus (peripheral and central mechs)
primary: mech and thermal hyperalg to damaged region (local) secondary: mech hyperalgesia throughout undamaged area (SPINAL mech) |
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What is the peripheral mechanism of sensitization?
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Chemical mediators of inflammation (subst P) activate mast cells-->histamine (C-fibers sensitive to this)
BV's swell All because of antidromic spikes (pain to SC sends collateral back to inj site to relase more subst P) |
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Nociceptive VS Neuropathic Pain
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Nociceptive: activation of pain from tissue injury
Neuropathic pain: direct injury to nerves (shingles, phantom limb) |
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What is referring pain? Cause?
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Reporting pain where nociceptors aren't active
Caused by convergence of nociceptive/visceral fibers onto same dorsal horn neuron |
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What is discriminative pain?
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Step on tack; VPL to S I, S II
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What path does affective pain take?
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SLOW PAIN
Reticular formation, intralaminar nucleus |
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Explain the mechanism behind the gate control theory.
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A delta C-fiber inhibit gate cell, activate AL syst (pain)
A-beta fiber activate gate cell, which inhibits AL syst Activating DC/ML system via touch helps ignore pain |
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Describe descending pathways to moderate pain.
How can this be mimicked? |
Periaqueductal Gray (midbrain)-->Nuc raphe-->Serotonin-->inhibits transmission of pain
Opiates use this same pathway!!!! PS this also means emotions (cerebrum) can control pain if they wanna |
