PSY333 JUNE 11.docx

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Nevena Simic

PSY333 JUNE 11, 2012 PAIN CHIEF SYMPTOM BRINGS PEOPLE TO PHYSCIIAN, DISCOMFORT SOMETHING ONE - Ecxaming psychsocial factors influence physical peop od geelin gpain - Can be useful to learn - And cause an unconscious response, before conscious sensation of pain move hand away preventing more damage - Also in learning in educating children reinforcement technique - More chronic then acute pain - Chronic is back pain common - Headchaches - Abdominal cyclic pain Significance of pain - Pain = symptom of chief concern to patients – leads them to seek medical attention - Pain not important thing to physican – think pain not as important bc what is casuinfthe pain secondary importance to underlying casue of symptom - Pain often considered of secondary importance to md - Patients fear pain in illness and treatment moset – fearing that the cant releie suffer – increase anxity - Most common reason for euthanasian - 4 billion is spent annually in canda on over the counter pain meds – most common tyleonol etc - To treat every day pain Why do we feel pain Pain is adaptive - Tells us to avoid behaviours that may hurt us - Forces us to rest and recover after an injury – maladaptive bad for resprodcition so cut out - Pain result of injury adaptive e to allow us chance to recurpate we need to rest so body can fiz - Can be reflexive and unconcius – hot stove burner – pull hand awa - Can beused as a learning mechanism - Electic shock for rats - Spanking for chidleren Pain as an inhinotuy mechanism - Inhibit behavior that preceed it - Operant conditioning – learning based on consequences based on one action have to tie to action - Positive=add negative take away - Reinforcement – consequence increases likelihood of nehaiour in future - Positive re – application of a desirable stumulus (reaward candy) - Negative reinforcement – removal of a negative stimulus (don’t hae to do a chore if good) - Punishment – consewquence decrease likelihood of behavior in the future - Positive punishment aplleication of acersivce stimulus (spanking) - Negative punishment – take away something good (tv time) Pain as an inhibotry mechanism - Using pain o learn - Posotove punishment and negative reinformcent - Both use adverse stimulkus - Involve aversive, potentially painful stmuli - Electrical shock - Spanking - Soothing burns Pain behaviours are behviours that occur in response to pain such as 1. Facial and audible expression of distress 2. Dostrotions in posture or gait – limb, fetal postion 3. Negative affect - sadness 4. Avoidance of activity – normally enage in – flag discormot What is pain – elusive nature Pain is a subjective experience - Degree to which pai is felt and how incapacitating it is depends on how it is interepreted - Cant visibily see it like a severed limb – same cut two people two levels of pain – degree feel and incapactiing depend on intereptet - Heaviliy influenced by context in which it is expreinced - Beechers eample of soldiers versus cicvillians - 25 percent wounded soldiers ask for morphine versus 80 percent of civialians after surgery civilians domestically car accident, - Measure how much morphine individual ask for – objective measure – pain withstand – compable surgeries – - Soldiers enforcing that they suruvued pain – civialian threatening rather then - More often more pain report sensitize - Sports injury continue to play – sns arousal diminishes pain senstivty – reduce it due to adranline tamped down on pain sensitivyt What is pain - can refer to many different sensation - sharp pain – nail - dull ache – back pain - blistering – sun burn - small but irritating – cut finger - also based on length how long acute pain - intense - shortlived - disapeara as injury heals - less then 6 months – 6 month then disaparte chronic - begin as acute - doesn’t go away - example lower back pain, headaches, arthrtits - recurrent acute – again and again (headache) vs intractable benig – not go away but not live threatening vs progressive – increasing in intensity over time – example cancer what is pain pain – an unopleasant sensory and emotional expericne assoacited with actual or potential tissue damageor described in terms of such damage internaltional ass for the study of pain iasp operationalziiton pain physiology - despite enormous caribailty in how we perceive pain there is an innate and hard wored physiological basis for pain - overview – free nerve endings in periphery - send messages to spinal cord - spinal tracts carry message to midbrain and thalamus - conscious attention in brain – cortex nociception - contact with stimulus – stimuli can be mechanical (pressure, punctures and cutes) or chemical (burns) - reception – a nerve ending senses the stimulus - transmission – a nerve sends the signal to the central nervous system. The rerlay of information usually involves several neurons with the cns - pain cnter reception – the brin receives the info for further processing and action – could be conscious or unconscious phys of pain - 3 kinds of pain perceptions )nociception) - Mechanical (crishing, tearing etc - Thermal (heat or cold) - Chemical (iodine in a cut, tear gas) - Differcens in types of pain attributed to difference in pain receptors (nociceptors) - Unevenly distributed in body – some more highly some non- none in brain (no pain receptors) - Once open dura matter some pain once removed and cortex exposed no need for pain relievers Contd Location-any area of the body that can sense pain either internally or externally - External – skin, cornea and mucosa - Internal – muscles, joints, bladder, gut Types of nocipetors - Classified based on which enivornmental modalities they respond to - Thermal – activated by noxious heat or cold at various temps - Mechanical – repsnf to exess pressure or mechanical deformationa (incision) - Chemical – respond to spices capsaicin and chemical agents acrolein - Polymodal – repson to more then one of these modalities (example mechanical and chemical) Nociceptors - Occurs in periphery - Hand external lcoaiton o n skin - 2 different types of axons - Once activated activates signal travels down axon of free nerve ending - 2 types - A delta fibers – myleinated – ap travel at 20 meter per sec- sharp pain – thermal and mecahincal - C FIBEERS AXONS – unmyleinated – ap travel at 2 meters per second – dull or aching pain - Sig of myalination 0 increases speed of transmission ans so sudden and intense pain is more rapidly condcutucred to cerebal cortex then is slocwer dull acing pain of c fiers Contd - Axons extend into pns - Cell bodies located in dorsal root ganglis of spinal cord - From and back - Back dorsal - Front is ventral and left and right for both horns - Left side info bodies to left - Before dorsal horn cell bodies in dorsa root ganglia Pain pathway - They synapse at dorsal horn - Making from periphery called first order enter spinal cord at dorsal horn - Dorsal horn divide into distinct layer (laminae) - A delta fibers connect to lamina 1 and 5 - C fibers synapse of lamina 2 - In spinal cord first oerder neurons project to second order neurons and cross midline to ascend to spine – enters right side then second order crosses to left of spine and makes way up to nrain left side brain right sensory info from right side body Contd 3 pain tracts - Spinothalmic – tract end in thalamus - Spinoreticular – into reticlualr formation - Spinomesencephlic - midbrain Sensory aspiectfs of pain - A delta fibers – project onto thalamus ad sensory areas of cerebral cortex Motivational/affective aspects - C fibers – thalamic, hypothalamicm cerebral cortex areas The brain can influence pain perception - Pain from cut on hand eventually subsides or reduces to a lower intensity - Brain to lower parts not uni from periphery - Top down - If you consciously distract yourself you don’t think about the pain and it others u less - Top down processes cut still there pain go away - People given placebos for pain control often report that the pain ceases to dimisnh Descending pain pathway - Ascending patheway to brain initiates conscious realization of pain - Descending patheay from brain modulates pain sensory – semsations modulated at dorsal horn - Cerebral awaultic – paraaquadactal grey signal to ray nucleus releases serotonian – and nucleus acts on reticular formation and sends to dorsal horn at exact location first order synapse to seconf order neuron - What descending pathway does releases opoid - Opoid eleviates pain – stop signal from 1 order to 2n d order neuron stop
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