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Is pain a conscious or unconscious experience?
conscious
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Which autonomic system does pain stimulate? Does pain increase or decrease metabolism? Protein/carb catabolic or anabolic? Water balance?
- sympathetic
- increases metabolism
- catabolic
- sodium and water retention
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What is another word for physiologic pain? is this conscious?
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What is another term for pathologic pain? Is this conscious?
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Physiologic v. pathologic pain: which is considered useful and aids to prevent tissue damage?
physiologic pain
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Physiologic v. pathologic pain: which is NOT useful and is pain felt in tissues that are damaged?
pathologic pain
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Is inflammation part of peripheral or central sensitization? does inflammation increase or lower stimulus threshold?
- peripheral sensitization
- lowers stimulus threshold
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What are two characteristics of peripheral sensitization? Does this happen at the site of injury?
- primary hyperalgesia
- allodynia
- yes, at tissue
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What contributes/what is central sensitization?
severe prolonged discharge of afferent neurons due to peripheral stimulation and neuropathic pain
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What fibers are first order? Where are these fibers?
- what/where are second order fibers?
- 1st: A-delta and C in periphery to dorsal horn
- 2nd: excitatory ascending neurons in dorsal horn
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In central sensitization, 1st order stimulates 2nd order which activates which receptors?
NMDA receptors --> exacerbates response to peripheral stimulus
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What are 2 characteristics of central sensitization?
- secondary hyperalgesia (AWAY from tissue)
- allodynia (at tissue)
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What are the 4 parts of pain process?
- transduction
- transmission
- modulation
- perception
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Do nociceptors have hi or low threshold for stimulus? What are 3 types of stimuli nociceptors respond to?
- hi threshold
- thermal, mechanical, chemical
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How are silent/sleeping nociceptors activated?
only by inflammatory mediators (not tissue damage)
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Which nociceptor is responsible for 1st pain? How is this pain described?
- A-delta
- sharp, discriminative
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Which nociceptor is responsible for 2nd pain? How is this pain described?
- C fiber
- slow/burning/aching
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What percentage of A-delta fibers act as nociceptors? What about C fibers?
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Where are silent/sleeping nociceptors found?
terminal end of A-delta and C fibers
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How do silent nociceptors contribute to hyperalgesia?
only stimulated by inflammatory mediators --> once activated, very sensitive to stimulus --> hyperalgesia (peripheral sensitization)
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Are A-delta or C fibers non-myelinated so slower discharge rate?
C fiber
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what part of pain process involves stimulating nociceptors to initiate action potential?
transduction
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What part of pain process is when AP travels 1st order neuron to dorsal horn to projection/2nd order neurons?
Transmission
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What part of pain process occurs in dorsal horn and nociceptive input can be reduced or increased, depending on release of neurotransmitters?
modulation
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Do neurotransmitters like GABA, serotonin, and norepinephrine reduce or enhance nociception?
reduce
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Do neurotransmitters like glutamate, prostanoids, acetylcholine, and substance P reduce or enhance nociception?
enhance
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What receptors are activated with central sensitization?
NMDA receptors
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What part of pain process occur in post-synapse of 2nd order neurons to relay modulation to brain?
projection
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What part of pain process integrates, processes, and produces autonomic/motor/endocrine response?
perception
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What are some differences between nociceptors in viscera v. somatic tissue?
- viscera has greater distance/fewer fibers, more K-opioid receptors, and stimulated by inflammation/ischemia/dilation
- viscera has sympathetic/parasymp fibers that transmit nociception
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