Week 9-10 (Pain and Respiration) Flashcards
<p>What is the definition of pain (2)</p>
<p>Unpleasant sensory and emotional experience associated with actual or potential tissue damage</p>
<p>Associated with crying, sympathetic activation, behavioural changes</p>
<p>Why is pain important? (2)</p>
<ul> <li>Directs attention to danger and holds attention to it</li> <li>Patients with congenital analgesia (cannot feel phyiscal pain) have reduced lifespan <ul> <li>e.g., biting off tonuges</li> </ul> </li></ul>
<p>What are the fixed factors influencing sensation of pain (4)</p>
<p>1. Genetics</p>
<p>2. Age (Older more pain)</p>
<p>3. Sex (Woman more pain)</p>
<p>4. Hair Colour (Redheads have increased sensitivity to thermal pain, and reduced sensitivity to chemical and electrical pain, need more anasthetic)</p>
<p>What are the modifiable factors influencing pain (6)</p>
<ul> <li>Context (High adrenaline increases tolerance)</li> <li>Prior life stressors (Early stress modifies later sensitivity)</li> <li>Obesity (Obseity associated with increased sensitvity, might be cormorbid)</li> <li>Anxiety/Depression (Increased sensitivity)</li> <li>Attention (Diverting attention reduces pain sensation)</li> <li>Sleep (Sleep deprivation increases pain sensitvity)</li></ul>
<p>What is the Gate Theory of Pain and what does it explain? (2)</p>
<p>Feedback loop in spinal cord to determine which stimuli reaches brain (Chronic stress opens gate; Adrenaline closes gate)</p>
<p>Explains how pain can be ignored on battlefield but intense when upset; Rubbing sore limbs/TENS (distractions) may "close gate"</p>
<p>What is the bioloigcal underpinns of Gate Theory of Pain (2)</p>
<ul> <li>Noxious stimulus sensed by smallperiphery nerve fibres and send to spinal cord</li> <li>Distractive stimulus sensed by large periphery nerve fibres and send to inhibitory interneuron and spinal cord. <ul> <li>Inhibitory interneuron reduces pain signal reaching the brain</li> </ul> </li></ul>
<p>What is the pain receptor (3)</p>
<p><u>Nociceptors</u></p>
<ul> <li>Sensory receptors capable of transducing noxious stimuli</li> <li>Free neve endings</li> <li>Several class which respond to different stimuli</li></ul>
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<p>What are the different stimuli in relation to pain receptors? (5)</p>
<p><u>Stimuli</u></p>
<ul> <li>Mechanical <ul> <li>E.g., pressing finger</li> </ul> </li> <li>Temperature(Extreme) <ul> <li>Will remain silent until extreme cold/heat</li> </ul> </li> <li>Electrical <ul> <li>Electrical shock/pain</li> </ul> </li> <li>Chemical <ul> <li>E.g., Capsaicin responds to heat</li> </ul> </li></ul>
<p>> Inflammation: NOinflammation receptor</p>
<ul> <li>Mechanical and increased nociceptor sensitivity</li></ul>
<p>What are the 2 kinds of pain nerves? (3)</p>
<ul> <li>Aδ (alpha-delta) fibres <ul> <li>Some myelin, faster for sharp pain; transmit sharp pain</li> </ul> </li> <li>C fibres <ul> <li>No myelin, slower, transmits dull aching pain</li> </ul> </li></ul>
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<p>If myelin speeds up speed of trasnmission, and pain is important, why are there so little myelin in the pain nerves? (2)</p>
<p>Pain signals are quick due to</p>
<ul> <li>Size of the nerves</li> <li>Number of synapses (few synapses = faster) <ul> <li>From spinal cord to brain has few to no synapses</li> </ul> </li></ul>
<p>Where is the synapse in the spinal cord? What does it release?</p>
<p>Pain signals synapse in the <u>substantia gelantinosa</u> in the<u> dorsal horn</u> of the spinal cord, releasing...</p>
<ul> <li>Glutamate</li> <li>Substance P <ul> <li>Small pain = Glutamate</li> <li>Large pain = Glutamate + P</li> </ul> </li></ul>
<p>What are the two sense pathways? (3 ea.)</p>
<p><u>Touch</u>: Mechanoreceptors</p>
<ul> <li>At ipsilateral side at spinal cord</li> <li>Transverse to contralateral side at medella</li> <li>To thalamus and to contralateral somatosensory cortex</li></ul>
<p><u>Pain:</u>Nocireceptors</p>
<ul> <li>Transverse to contralateral side at spinal cord</li> <li>At contralateral side at medella</li> <li>To thalamus and to contralateral somatosensory cortex</li></ul>
<p>What are the ascending pain pathways, i.e. where are the places pain signals terminate? (3)</p>
<ul> <li>Primary somatosensory cortex (Where)</li> <li>Anterior Cingulate (Sense of pleasantness) <ul> <li>Emotional aspects</li> <li>Sympathetic pain</li> <li>Social rejection (not the same as pain sensation)</li> </ul> </li> <li>Insular (Also has somatosensory distrbution) <ul> <li>Modulate physical pain response</li> </ul> </li></ul>
<p>What are the descending pain pathways, i.e. which brain areas modulatespain? (2)</p>
<p>Amygdala and Hypothalamus modify pain responses by activating periaqueductual gray (PAG)</p>
<p>PAG usesendorphins/endogenous morphine, inhibiting pain signals (Endorpins bind to opiate receptor in PAG)</p>
<p>How does the brain deal with prolonged pain? (1)? What else cause endorphin release? (1)</p>
<p>Since it is unnecessary, brain dimishes prolonged pain through endorphin release, which binds to opiate receptors in PAG</p>
<p>Inescapable pain, exercise, sex leads to increased endorphin release and reduced pain sensitivity</p>
<p>What are some 4drug treatments for pain?</p>
<p>1. Opiates</p>
<p>2. Panadol/Tylenol</p>
<p>3. Placebo</p>
<p>4. Acupuncture</p>
<p>Drug treatment #1: Opiates (2)</p>
<p>Blocks release of substance P in PAG</p>
<p>Same mechanism as endorphines</p>
<p>Drug treatment #2: Panadol/Tylenol (3)</p>
<ul> <li>Exact mechanisms of analgesia unkown.</li> <li>Inhibits synthesis of prostaglandins (pro-inflammatory)</li> <li>Analgesia is presumed central and related to reduced serotonin, opioids or through the endogenous cannabinoid system as blocking these systems reduce the analgesic effect.</li></ul>
<p>Drug treatment #3: Placebo (2)</p>
<ul> <li>Quite effective</li> <li>Reduce emotional aspects of pain via. reduced activity in cingulate cortex (not somatosensory)</li> <li>Increased release of endorphins (Placebo + Naxolene < Placebo due to placebo effect)</li></ul>
<p>Drug treatment #4: Acupuncture</p>
<p>Acupuncture releases endogenous opioids</p>
<p>Evidence that social exclusion hurts?</p>
<ul> <li>ACC activation in virtual ball game. <ul> <li>Activation correlated to extent one felt excluded</li> </ul> </li></ul>
<p>Evidence of heartbreak and pain</p>
<p>Recount recent unwanted breakup while viewing ex's picture<strong>vs</strong>painful stimulus</p>
<ul> <li>Same brain regions in both conditions (ACC, Insula, Somatosensory)</li> <li>Similar findings in bereaved indiviuals</li></ul>
<p>Evidence ofTylenol for social pain (3)</p>
<ul> <li>Tylenol participants had reduced daily hurt feelings over time (vs placebo didn’t change)</li> <li>Tylenol had low activation of ACC & insula after virtual ball game</li></ul>
<p>Evidence of love and pain?</p>
<ul> <li>Painful stimuli in 7 conditons</li> <li>Holding their partner’s pic/hand = Reduced pain ratings</li> <li>Holding a stranger’s hand / ball = No improvement in pain ratings</li></ul>
<p>Note: 44% reduction in pain rating when viewing a picture of their partner compared to holding hand</p>
<p>Evidence that hyponsis alters pain?</p>
<p><u>Methods</u></p>
<p>Arms in ice water. Hypnosis vs no hypnosis</p>
<p><u>Results</u></p>
<ul> <li>Hypnotised group rated pain just as intense but less unpleasant</li> <li>Hypnosis alters activity in: ACC, Amygdala, Thamalus, Insula, Somatosesnsory cortex (Same areas)</li></ul>
<p>Define Chronic Pain (4)</p>
<ul> <li>Pain that outlasts expected healing time (3-6mo)</li> <li>Generally not due to residual injury/inflammation <ul> <li>Poor correlation with signs of injury and pain (20-25% osteoarthrities patients who have knee replcement don't get improvement in pain)</li> </ul> </li> <li>Prevalance is about 10-50%, depending on type of pain</li> <li> <p>Increased pain sensitvity is a good indicator of future chronic pain</p> </li></ul>
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<p>What are predisposing factors to Chronic Pain? (5)</p>
<ul> <li>Women <ul> <li>1.5-2x higher pain sensitivity and double rate of chronic pain</li> </ul> </li> <li>Early life pain/stress and prior injury <ul> <li>Increase adult pain sensitivty/persistent pain</li> </ul> </li> <li>Stress <ul> <li>Rat pups separated from mum have pain signs</li> </ul> </li> <li>Psychological/Personality factor <ul> <li>Fear of pain, catastrophising</li> </ul> </li> <li>Depression/Anxiety <ul> <li>Reciprocal</li> </ul> </li></ul>
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<p>What is the pathophysiology of chronic pain. (4)</p>
<p>Due to neuroplasticity both peripherally and centrally</p>
<ul> <li>Peripheral changes in multiple receptors</li> <li>Neurons grow and increase synaptic connections to second order neurons in medulla</li> <li>Gilal cellsinspinal cord remodel to intensify pain trasmission (e.g., produce substance P)</li> <li>CNS changes resulting in central sensitisation <ul> <li>Pain signals without pain stimulus</li> <li>Lower pain threshold</li> </ul> </li></ul>
<p>Pain becomes a disease itself</p>
<p>What is the link between depression and chronic pain? (3)</p>
<ul> <li>Bidirectional (65% depression have chronic pain;50% chronic pain have depression;Longitudinal studies depressive symptoms predict future pain)</li> <li>Comorbid patients have: <ul> <li>More intense pain</li> <li>Greater disability from pain</li> <li>Poorer response to pain treatment</li> </ul> </li> <li>Treating depression improves pain treatment</li></ul>
<p>Psychological Interactions of Depression vs Normal in Chronic Pain</p>
<p><u>Psychological Interactions</u></p>
<p>Injury > Pain experience</p>
<p>Depression:</p>
<ul> <li>Pain <strong>catastrophizing</strong> > Fear > ... > Pain experence</li></ul>
<p>Normal:</p>
<ul> <li>No Fear > Confrontation > Recovery</li></ul>
<p>What is the relationship between meditation and pain?</p>
<p>Pain reduced following mindfulness meditaiton</p>
<ul> <li>Reduced pain-related activation of somatosensory cortex and insula</li> <li>Increased activation of ACC (Contrary to expectation)</li> <li>Reduced amygdala activation andnegative emotions in responseto pain</li> <li>NOT DUE TO ENDORPHINS <ul> </ul> </li></ul>
<p>What is the link between sleep and pain? (2)</p>
<ul> <li>High comorbidity: 55-88%</li> <li>Bidirectional <ul> <li>Sleep disruption and insomnia increases risk of chronic pain</li> <li>Pain inhibits sleep</li> </ul> </li></ul>