Term
| does pain arise from excessive stimulation of mechanoreceptors |
|
Definition
|
|
Term
| what receives and conveys painful sensory signals to the CNS |
|
Definition
| dedicated receptors and pathways |
|
|
Term
| what is the name of receptors that receive pain signals |
|
Definition
|
|
Term
| why does it make good sense to have a separate system for the detection of pain and mechanical stimulation |
|
Definition
| don't want to confuse pain with squeezing, for example |
|
|
Term
| what are the 2 classifications of receptors based on morphology |
|
Definition
| encapsulated, free nerve endings |
|
|
Term
| what do encapsulated receptors detect |
|
Definition
|
|
Term
| what do free nerve endings detect |
|
Definition
| pain and temperature stimuil |
|
|
Term
| are free nerve endings myelinated |
|
Definition
| no, or else they're very lightly myelinated |
|
|
Term
| are free nerve endings big |
|
Definition
|
|
Term
| are free nerve endings fast |
|
Definition
|
|
Term
|
Definition
| unspecialized free nerve endings that intitiate the sensation of pain |
|
|
Term
| what sensations do nociceptors carry |
|
Definition
|
|
Term
| do nociceptor axons conduct quickly or slowly |
|
Definition
|
|
Term
| what are the 2 categories of nociceptors |
|
Definition
|
|
Term
| what determines which category a nociceptor falls into |
|
Definition
|
|
Term
| what are the axon properties of a delta nociceptors (myelinated? Conduction speed? Diameter? What kind of stimuli it responds to?) |
|
Definition
| lightly myelinated. 20 m/s. medium diameter. responds to dangerously intense stimuli |
|
|
Term
| what are the axon properties of c fiber nociceptors (myelinated? Conduction speed? Diameter? What kind of stimuli it responds to?) |
|
Definition
| unmyelinated. 2 m/s. small diameter. Responds to innocuous temperature, itch |
|
|
Term
| what is the faster pain pathway |
|
Definition
|
|
Term
| what is the slower pain pathway |
|
Definition
|
|
Term
| what is the pathway of initial pain |
|
Definition
|
|
Term
| what is the pathway of chronic pain |
|
Definition
|
|
Term
| If I were to take a little electrode and put electrical impulses in an A beta fiber, would it convey pain? |
|
Definition
|
|
Term
| if I were to take a little electrode and put electrical impulses in an A delta fiber, would it convey pain? |
|
Definition
|
|
Term
| how do we know that a Beta fibers don't convey pain |
|
Definition
| experimental evidence: direct electrical stimulation at any intensity/frequency does not produce pain in A beta fibers, but stimulation of A delta and C fibers does produce pain |
|
|
Term
| what do mechanothermal nociceptors detect |
|
Definition
| potentially harmful thermal stimuli |
|
|
Term
| what do non-nociceptive thermoreceptors detect |
|
Definition
| innocuous, non-harmful warm and cold temperatures |
|
|
Term
| describe the firing rate of non-nociceptive thermoreceptors as a temperature gets hotter and hotter |
|
Definition
| the firing rate of non-nociceptive themoreceptors stays about the same as at lower temperatures |
|
|
Term
| describe the firing rate of mechanothermal nociceptors as a temperature gets hotter and hotter |
|
Definition
| mechanothermal nociceptor axons increase their firing rate as temperature gets dangerously hot |
|
|
Term
| are the receptive fields of all pain and temperature sensitve neurons large or small |
|
Definition
|
|
Term
| why are the receptive fields of pain and temperature sensitive neurons large |
|
Definition
| the detection of pain is far more important than the exact location |
|
|
Term
| what do we call the specific receptors associated with nociceptive afferent nerve endings |
|
Definition
|
|
Term
| what is another term for vanilloid receptors |
|
Definition
|
|
Term
| in what types of fibers are VR-1 receptors found |
|
Definition
|
|
Term
| what makes VR 1 a transmembrane receptor |
|
Definition
| it has a channel/central pore in the middle |
|
|
Term
| what activates VR-1 receptors |
|
Definition
| heat: temp greater than 45C |
|
|
Term
| what happens when VR 1 receptors are activated and opened |
|
Definition
| the channel allows an influx of sodium and calcium ions which generate action potentials in the nociceptive axon |
|
|
Term
| how does capsacin affect VR 1 receptors |
|
Definition
| capsaicin is cell-permeant. It can bind to the intracellular part of the receptor causing the receptor to open |
|
|
Term
| what 2 things activate VR-1 receptors |
|
Definition
|
|
Term
| what happens when capsaicin is applied to the skin |
|
Definition
| produces a burning pain and elicits hyperalgesia to thermal and mechanical stimuli |
|
|
Term
|
Definition
| increased sensitivity to pain |
|
|
Term
|
Definition
| .75% capsaicin. Helps desensitize nerve endings to treat arthritis and neuritis. |
|
|
Term
| why is the area surrounding an injury (cut or bruise) so painful |
|
Definition
| because damaged tissues release substances that change responsiveness of nociceptors |
|
|
Term
| what local substances are released following injury y damaged tissues |
|
Definition
| prostaglandins, histamine, ATP, bradykinins, substance p |
|
|
Term
| what is inflammatory soup |
|
Definition
| term to describe the release of prostaglandins, histamine, ATP, bradykinins, and substance P following tissue damage |
|
|
Term
|
Definition
| large molecule neurotransmitter |
|
|
Term
| what is peripheral sensitization |
|
Definition
| the change in responsiveness of nociceptors caused by the inflammatory soup following injury |
|
|
Term
| how do released prostaglandins change the responsiveness of nociceptors following injury |
|
Definition
| released prostaglandins reduce the threshold of depolarization required to generate action potentials in nociceptive neurons, thereby increasing neuronal activity |
|
|
Term
| how does bradykinin change the responsiveness of nociceptors following injury |
|
Definition
| increases the activity of VR-1 receptors |
|
|
Term
| how does substance P change the responsiveness of nociceptors following injury |
|
Definition
| causes mast cells to release histamine, which causes vasodilation |
|
|
Term
| what releases substance P following tissue damage |
|
Definition
|
|
Term
| once you get inflammatory soup and you've reduced the threshold by which an action potential can get fired in a nerve ending, what is the result of a littl ebit of pressure |
|
Definition
| a little bit of pressure is enough to fire action potential in pain fibers |
|
|
Term
| what is the purpose of inflammatory soup |
|
Definition
| protect injured tissue, promotes healing, guards against infection |
|
|
Term
| how does inflammatory soup promote healing |
|
Definition
|
|
Term
| how does inflammatory soup guard against infection |
|
Definition
|
|
Term
| how do anti-inflammatory agents like aspirin reduce pain |
|
Definition
| by inhibiting cyclooxygenase |
|
|
Term
|
Definition
| an enzyme important in the biosynthesis of prostaglandins |
|
|
Term
| what happens if you don’t' form prostaglandins |
|
Definition
| you don't supercharge the sensory nerves so you decrease the pain |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| what happens in hyperalgesia |
|
Definition
| stimuli that don't usually cause pain are perceived as painful |
|
|
Term
|
Definition
| peripheral sensitization of afferent receptors |
|
|
Term
| how does hyperalgesia change as tissues heal |
|
Definition
| the sensitization of peripheral nerves typically declines and pain thresholds return to preinjury levels |
|
|
Term
| what can happen with hyperalgesia in someone with diabetes, stroke, MS |
|
Definition
| sensitization can persist |
|
|
Term
|
Definition
| persistent sensitization/hyperalgesia. A chronic painful condition that is difficult to treat |
|
|
Term
| what are central pain pathways |
|
Definition
| pathways that convey information concerning potentially noxious stimuli to the brain |
|
|
Term
| what are the 2 components of central pain pathways |
|
Definition
| sensory discriminative component, affective-motivational component |
|
|
Term
| what does the sensory discriminative component of the central pain pathway do |
|
Definition
| signals the location and intensity of a noxious stimulus |
|
|
Term
| what does the affective-motivational component of the central pain pathway do |
|
Definition
| signals the unpleasant quality of the experience |
|
|
Term
| what pathways does the sensory discriminative component of the central pain pathway depend on |
|
Definition
| depends on pathways that target the traditional somatosensory complex |
|
|
Term
| what pathways does the affective motivational component of the central pain pathway depend on |
|
Definition
| depends on cortical and brainstem pathways that go to other areas of the brain (not the traditional somatosensory complex) |
|
|
Term
| what is the spinothalamic tract |
|
Definition
| a pathway responsible for the discriminative component of pain |
|
|
Term
| how do pain and temperature reach the primary sensory cortex |
|
Definition
| through the spinothalamic tract |
|
|
Term
| how many neurons in the spinothalamic tract |
|
Definition
|
|
Term
| what do we call the neurons in the spinothalamic tract |
|
Definition
| 1st order, 2nd order, 3rd order neurons |
|
|
Term
| what is the spinothalamic tract sometimes called |
|
Definition
|
|
Term
| what does the spinothalamic pathway convey |
|
Definition
| conveys pain and temperature stimuli from the body |
|
|
Term
| why is the spinothalamic pathway sometimes called the anterolaterarl system |
|
Definition
| because it rises up in the anterolateral part of the spinal cord |
|
|
Term
| aside from pain and temperature, the spinothalamic tract can carry crude sensations of what? |
|
Definition
|
|
Term
| if you lose your mechanosensory pathway, could you still feel a little bit of touch? |
|
Definition
| yes, from the pain pathway |
|
|
Term
| where are the cell bodies of the 1st order neurons of the spinothalamic trat located |
|
Definition
|
|
Term
| where are the peripheral processes of the 1st order neurons of the spinothalamic tract |
|
Definition
| their peripheral processes end in free nerve ending nociceptors |
|
|
Term
| where are the central processes of 1st order neurons of the spinothalamic tract |
|
Definition
| their central processes enter the dorsal horn of the spinal cord |
|
|
Term
| where do 1st order neurons synapse on 2nd order neurons of the spinothalamic tract |
|
Definition
| dorsal horn of the spinal cord |
|
|
Term
| in the spinothalamic tract, what do 2nd order neurons do after being synapsed on by 1st order neurons in the dorsal horn of the spinal cord |
|
Definition
| cross the midline and ascend the spinal cord via the spinothalamic tract |
|
|
Term
| what order neurons cross in the spinothalamic tract |
|
Definition
|
|
Term
| in the spinothalamic tract, where do 2nd order neurons carrying pain sensation from the body synapse on 3rd order neurons |
|
Definition
| within the ventral posterior lateral nucleus of the thalamus |
|
|
Term
| in the spinothalamic tract, where do 3rd order neurons project to |
|
Definition
| 3rd order neurons project to the somatosensory cortex via the internal capsule |
|
|
Term
| what do the 3rd order neurons of the spinothalmaic tract travel on to get to the somatosensory cortex? |
|
Definition
|
|
Term
| through what path do sensory neurons in the DRG enter the spinal cord |
|
Definition
|
|
Term
| what are the 2 divisions through which sensory neurons enter the dorsal root |
|
Definition
| lateral division, medial division |
|
|
Term
| what axons enter the dorsal root through its lateral division |
|
Definition
| a delta and C axons carrying pain and temperature information |
|
|
Term
| what axons enter the dorsal root through its medial division |
|
Definition
| Abeta and groups 1, 2 carrying mechanosensory information |
|
|
Term
| what do centrally projecting nociceptive axons do when they reach the dorsal horn? |
|
Definition
| they branch into ascending and descending collaterals called Lissauer's Tract |
|
|
Term
| what is the area that pain/temperature snsory nerves are in as soon as they get to the cord from the dorsal root |
|
Definition
|
|
Term
| what do pain/temp axons do before penetrating the gray matter of the dorsal horn |
|
Definition
| they run up and down the spinal cord for 1-2 segments |
|
|
Term
| in what regions of the spinal cord do spinothalamic tract 1st order neurons synapse? |
|
Definition
| Rexed's Laminae: Laminae I-V |
|
|
Term
| is Lissauer's tract associated with nociception or with mechanical reception? |
|
Definition
|
|
Term
| If you touch a candle with your index finger, where will that sensory information penetrate the spinal cord |
|
Definition
| C5-T1. (first enters dorsal root at C7, then takes Lissauer's Tract up or down 1 or 2 segments) |
|
|
Term
|
Definition
| nerve cell layers in the spinal cord. 10 descriptive divisions of the gray matter. |
|
|
Term
| what is Rexed Lamina I called |
|
Definition
|
|
Term
| what is Rexed Lamina II called |
|
Definition
|
|
Term
| what are Rexed's Laminae III-V referred to as |
|
Definition
|
|
Term
| what part of Rexed's Laminae do C fibers project to |
|
Definition
|
|
Term
| what part of Rexed's Laminae do A delta fibers project to |
|
Definition
|
|
Term
| what do 2nd order neurons from lamina 1&5 do after being synapsed on by 1st order neurons |
|
Definition
| cross the cord and ascend in the spinothalamic tract |
|
|
Term
| describe how there are modality sensitive neurons in Rexed's Laminae |
|
Definition
| modality sensitive neurons exist in Rexed's Laminae that convey noxious and innocuous sensory information to the spinothalamic pathway. |
|
|
Term
| what are some types of modality sensitive neurons in Rexed Laminae |
|
Definition
| neurons sensitive to: sharp/dull/burning pain; innocuous warm and cold temps; itch; lactic acid |
|
|
Term
| how do 1st order neurons of the spinothalamic tract enter the spinal cord |
|
Definition
|
|
Term
| in spinothalamic tract, where are the 2nd order neurons that 1st order neurons synapse on |
|
Definition
| Rexed's Laminae: Laminae I-V |
|
|
Term
| what are the names of the Rexed's Laminae where 2nd order neurons of spinothalamic tract are synapsed on by 1st order neurons |
|
Definition
| marginal zone, substantia gelatinosa, nucleus propius |
|
|
Term
| which order neurons in spinothalamic tract cross over |
|
Definition
|
|
Term
| what is the destination of 2nd order neurons traveling on the spinothalamic tract |
|
Definition
|
|
Term
| what do 2nd order neurons of spinothalamic tract do in VPL of thalamus |
|
Definition
| synapse on 3rd order neurons |
|
|
Term
| what do 3rd order neurons of spinothalamic tract do |
|
Definition
| project to somatic sensory cortex via internal capsule |
|
|
Term
| is the spinothalamic tract the sensory discriminative component or the affective-motivational component of central pain pathways to the CNS |
|
Definition
|
|
Term
| what mediates the affective-motivational aspect of pain |
|
Definition
| several projections arising from the spinothalamic pathway to several other cortical and brainstem regions |
|
|
Term
| what are the cortical and brainstem regions that receive nociceptive information that signal the unpleasant quality of pain from the spinothalamic pathway |
|
Definition
| reticular formation, parabrachial nucleus, intralaminar nuclei of the thalamus |
|
|
Term
| where is the parabrachial nucleus |
|
Definition
|
|
Term
| what happens to nociception information that is projected from the spinothalamic tract to the parabrachial nucleus of the pons |
|
Definition
| it is projected to the hypothalamus and amygdala |
|
|
Term
| what are the hypothalamus and amygdala important for |
|
Definition
|
|
Term
| along with the hypothalamus and amygdala, where else does the parabrachial nucleus project nociception information |
|
Definition
| periaqueductal gray matter of the midbrain |
|
|
Term
| what is the periaqueductal gray matter of the midbrain important for |
|
Definition
| monitoring descending pain pathways to limit how much pain info can come up to our brain |
|
|
Term
| what happens to nociception information that is projected from the spinothalamic tract to the laminar nuclei of the thalamus |
|
Definition
| it is distributed to the frontal lobe, insula, and cingulate cortex |
|
|
Term
| what are the frontal lobe, insula, and cingulate cortex all involved with |
|
Definition
|
|
Term
| Here are the bottom lines concerning central pain pathways |
|
Definition
| 1. Full experience of pain involves the cooperative action of extensive network of brain regions. 2. These pathways and regions are only beginning to be understood. 3. The prominent role of these networks in pain perception is evident by the fact that ablation of the sensory cortex does not eliminate chronic pain |
|
|
Term
| how do we know that multiple networks are involved in pain perception |
|
Definition
| ablation of the sensory cortex does not eliminate chronic pain |
|
|
Term
| what is brown-sequard syndrome |
|
Definition
| clinical presentation following spinal cord hemisection injury |
|
|
Term
| what does spinal cord hemisection result in |
|
Definition
| loss of ipsilateral mechanosensory, loss of contralateral pain and temperature sensation |
|
|
Term
| what carries pain and temperature information to the CNS from the face |
|
Definition
|
|
Term
| how many neurons in the trigeminothalamic tract |
|
Definition
|
|
Term
| which order neurons in trigeminothalamic tract cross over |
|
Definition
|
|
Term
| where are the cell bodies of the 1st order neurons of the trigeminothalamic tract located |
|
Definition
|
|
Term
| where do the 1st order neurons of the trigeminothalamic tract project centrally |
|
Definition
| into the spinal nucleus of trigeminal in the medulla |
|
|
Term
| in the trigeminothalamic tract, where do 1st order neurons first enter the brainstem |
|
Definition
| pons. They then descend to the medulla |
|
|
Term
| in the trigeminothalamic tract, where do 1st order neurons synapse on second order neurons |
|
Definition
| spinal nucleus of trigeminal in the medulla |
|
|
Term
| in the trigeminothalamic tract, where do 2nd order neurons cross the midline |
|
Definition
|
|
Term
| in the trigeminothalamic tract, how do 2nd order neurons ascend |
|
Definition
| through the trigeminothalamic tract |
|
|
Term
| in the trigeminothalamic tract, where do 2nd order neurons synapse on 3rd order neurons |
|
Definition
| ventral posterior medial nucleus of the thalamus |
|
|
Term
| in the trigeminothalamic tract, what do 3rd order neurons do after being synapsed on by 2nd order neurons |
|
Definition
| project from the VPM to the somatic sensory cortex via the internal capsule |
|
|
Term
| in the trigeminothalamic tract, how do 3rd order neurons go from the thalamus to the somatic sensory corte |
|
Definition
|
|
Term
| does damage to the somatic sensory cortex or internal capsule affect pain and temperature sensation from ipsilateral or contralateral face |
|
Definition
|
|
Term
| does the VPM or VPL receive nociceptive axons from body and limbs? |
|
Definition
|
|
Term
| does the VPM or VPL receive nociceptive axons from face? |
|
Definition
|
|
Term
| how do soldiers and battle or extreme athletes experience little to no pain despite physiologic demands? |
|
Definition
| our CNS has the ability to modulate how much pain can come in |
|
|
Term
| what experiments helped show that the CNS can modulate pain |
|
Definition
| electrical stimulation of periaqueductal gray matter produced pain relief |
|
|
Term
| how does the stimulation of periaqueductal gray matter produce pain relief |
|
Definition
| by activating descending pain-modulating pathways |
|
|
Term
| what 5 places in the brain have descending modulatory systems |
|
Definition
| somatosensory cortex, hypothalamus, periaqueductal gray matter, raphe nuclei, other nuceli in the rostral medulla |
|
|
Term
| where do descending pain modulating pathways project to |
|
Definition
| to neurons in the dorsal horn of the spinal cord and/or to the spinal trigeminal nucleus |
|
|
Term
| what do the descending pain modulating systems modulate once they have reached the dorsal horn of the spinal cord and/or the spinal trigeminal nucleus |
|
Definition
| they modulate the transmission of incoming/ascending pain signals |
|
|
Term
| where do serotonin neruons originate |
|
Definition
|
|
Term
| what do the descending pain modulating systems use to modulate pain |
|
Definition
|
|
Term
| what types of neurotransmitters do the descending pain modulating systems use to modulate pain |
|
Definition
| acetylcholine, norepinephrine, and opioids |
|
|
Term
| what do the neurotransmitters released by the descending pain modulating systems do |
|
Definition
| inhibit or facilitate incoming nociceptive information |
|
|
Term
| overall, what is the function of the descending pain modulating systems |
|
Definition
| balance the efficacy of nociceptive transmission |
|
|
Term
| are there more descending pathways to limit pain or are there more axons that bring pain signals in? |
|
Definition
| more descnding pathways to limit pain than axons that bring pain signals in |
|
|
Term
| what is the gate theory of pain |
|
Definition
| local interactions between mechanoreceptive afferents and neural circuits in the dorsal horn can help modulate incoming nociceptive stimuli |
|
|
Term
| what exactly happens in gate theory to modulate incoming nociceptive stimuli |
|
Definition
| mechanosensory Abeta axon terminals activate local circuit interneurons that inhibit incoming nociceptive stimuli |
|
|
Term
| when does morphine produce analgesia |
|
Definition
| when applied to regions associated with descending pain modulating pathways |
|
|
Term
| when were endogenous opioids discovered |
|
Definition
|
|
Term
| where are endogenous opioids |
|
Definition
| in the pain modulatory pathways |
|
|
Term
| what do endogenous opioids modulate |
|
Definition
|
|
Term
| wherever we have descending pain modulating pathways, what goes with them |
|
Definition
|
|
Term
| do endogenous opioids work centrally or peripherall |
|
Definition
|
|
Term
| how do endogenous opioids modulate pain transmission |
|
Definition
| local circuit interneurons in the dorsal horn synapse with axon terminals of nociceptive afferents, which are also synapsing with 2nd order neurons. The interneurons release endogenous opioids to modulate the activity of the ascending 2nd order neuron. interneurons are also targets of descending pain modulating pathways. |
|
|
