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Stack #215282
Neuro Unit II Lecture 6
| Question | Answer |
|---|---|
| Name the four kinds of pain that occur independent of normal nociceptor activation. | Inflammatory, Referred, Neuropathic, Thalamic/Spinal/Phantom |
| What causes inflammatory pain and give an example | A change in sensitivity of the nociceptors. Arthritis |
| What causes Referred pain? | Convergence of visceral and somatic inputs. Like in lamina V. |
| What causes neuropathic pain and give an example | Irritation of nociceptor axons like in sciatica |
| What causes thalamic/spinal/phantom pain? What is another name for this? | Abnormal activity of neurons in the anteriolateral system. Called central pain. Unrelated to the periphery |
| What are the two consequences of nociceptor sensitization? What fibers does this happen with? | Pain response to normal stimuli (due to decreased threshold) cld allodynia. Increase in intensity of response to stimuli called hyperalgesia. Happens with C polymodal fibers mostly |
| What are the causes of nociceptor sensitization? | 1. Release of lots of bad chemicals due to damage of tissue that cause nociceptors to lower threshold or activate AP directly 2. Axon reflex |
| What is axon reflex? | Nociceptor is activated, it releases subs P, lowering neighboring neurons thresholds. Get vasodialat, swell, redness around lesion. The incr. blood flow spreads the bad chems around lowering other neurons threshlds. So react more readily to benign stim. |
| What chemicals can cause the direct activation of nociceptors? | histamine, bradykinin, prostaglandins, erotonic, K+ |
| What can drugs can control sensitization and what do they work on? | NSAIDS: inhib prostagl. form. Capsaicin: activ. nociceps. and eventually deplete all subs P so no more sensit. of neighboring cells |
| Difference between analgesic and anesthetic | analgesic - block pain only anesthetic - block nociceptor from forming AP, so get no pain OR touch!! |
| What is the central component of sensitization? | Repeated stim of C fibers: AMPA channels stim by glutamate/Subs P in SC. Start depol. Depol causes NMDA channels to unblock (lose Mg plug). EVEN more depol. More depol, more NMDA channels open! Increased excitability of ALS! Amplification by wind up |
| What are the peripheral components that cause sensitization? | Bad chemicals lower your threshold and activate you, so you Lower neighbors thresholds, and spread the bad chemicals around!! |
| What causes central sensitization? | Repeated activ. of C fibers, end up with lots of unblocked NMDA channels. Have increased excitability of ALS! |
| What causes referred pain? | Crossed wires! Conduction and stimulus detection are fine. Its faulty localization! |
| Defn referred pain | Pain from visceral organs perceived as coming from a different area of the body. converge somatic and visceral nociceptive inputs to dorsal horn spinothalamic tracts. |
| What is faulty in sensitization? What about referred pain? What is normal in each? | Sensitization has faulty stimulus detection, referred pain has faulty localization. Both have normal conduction. Referred pain has normal stimulus detection. |
| What kinds of mechanisms cause radicular pain? | bypass normal activation of nociceptors. caused by mechanical compression or irritation of sensory nerve fibers |
| What kind of abnormality is radicular pain? | conduction abnormality |
| Chronic inflammation of chronically injured nerves can cause _________ unrelated to noxious stimuli. | radicular pain |
| How can radicular pain cause sensitization?? | Radicular pain starts the AP in middle of axon. Axon can propagate backwards, and cause release of subs P, which lowers threshold of neighbors! |
| What causes central pain? | Damage to the ALS |
| What causes phantom pain? | hyperactive neurons in the ALS due to imbalance b/w excitatory and inhibitory input after the loss of afferents in the leg (used to have MORE inputs, but amputated leg decr. them.) |
| What are phantom sensations? | Feeling of pain in an amputated limb. |
| T/F Central Pain is caused by activation of sensory receptors. | FALSE!! In amputees, there ARE NO sensory receptors left!! The leg is gone! |
| What can cause central pain besides amputation? | Lesion or problem that causes loss of the neurons that inhib pain (ie from preaquadu. and l. cerelus). Gives increased excitability similar to neuropathic pain |
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StudyBuddies
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