ch 11 definitions

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Published on 23 Jul 2011
Simon Fraser University
PSYC 365
Chapter 11: Pain
Afferent (sensory)
-Nerve cells that conduct impulses form a sense organ to central nervous site, or from lower to higher level sin spinal cord and brain
Nociceptors -Afferent nerve endings that respond to pain stimuli
A-delta fibres-Afferent peripheral fibres that’s associated with transmitting sharp, distinct pain
-Small myelinated fibres that transmit impulses very quickly
C-fibres-Afferent peripheral fibres that’s associated with transmitting diffuse, dull or aching pain
-Transmit impulses slowly because not myelinated
-Mostly determine motivational and affective elements of pain, which send pain messages to brain stem and lower portions of forebrain
-Comprise 60% of all sensory afferents, involved when pain is diffuse, dull or aching
Substantia gelatinosa -First two layers where sensory input is thought to be modulated
-Sensory aspects of pain strongly influenced by activity in A-delta fibres which send messages through thalamus on their way to cerebral
Gate control theory -Suggests neural mechanism in dorsal horns of spinal cord acts like a gate that can increase or decrease flow of nerve impulses from peripheral
fibres to central nervous system thereby influencing sensation of pain
-Pain not sensation that’s transmitted directly from peripheral nerve endings to brain, rather sensations are modified as they are conducted to
brain by way of spinal cord, also influenced by downward pathways from brain that interpret experience
-Gate-like mechanism that is able to control flow of pain stimulation to brain
-Information enters dorsal horns by way of primary afferent neurons; information passes through substantia gelatinosa, where information is
modulated by stimulation from periphery as well as by feedback from fibres descending from brain affects activity of transmission cells
causing them to either conduct (excitatory influence) or not (inhibitory influence) pain sensations to brain
-Small A and C fibres open gate, large A-beta fibres tend to close gate
-Gate may be closed by activity in spinal cord and by messages descending from brain
Central control trigger-In gate control theory of pain, specialized system of large-diameter, rapidly conducting fibres that activate selective cognitive processes that
then influence, by way of descending fibres, the opening and closing of gate
-Experience of pain is influenced by past experience, attention, and other cognitive activities through the central control trigger
-Affective reactions (ex. Anxiety, focus, fear) can exacerbate experience by affective central control and opening gate
-Intense involvement in relaxation, positive experiences can mute pain experience and cause gate to close
Phantom limb pain-Experience of pain in an absent body part
-Common to those who have undergone amputation, limb very vivid to amputee, can tell you precise position of phantom,
-Phantom limb behaves very much like normal limb, moves in perfect coordination with other limbs, can experience many sensations ; 80%feel
Neuromatrix theory-Extension to gate control theory, which greater emphasis placed on brain’s role in pain perception; genetically determined neuromatrix or
network of brain neurons distributed throughout many areas of brain, widespread network of neurons that generates patterns, processes
information that flows through it and produces pattern felt as a whole body
Neurosignature patterns-Neuromatrix-generated patterns
-Patterns may be generated from sensory input, or innately produced (phantom limb)
-Responsible for producing a multidimensional experience of pain
Periaqueductal grey area-Area of the midbrain that’s involved in pain reception
Acute pain-Pain that lasts less than six months and serves to warn of impending tissue damage or need for convalescent rest (ex. Toothache, broken limb)
-Physiological response seems partly proportional to stimulus intensity
-Cause considerable anxiety and distress, painkillers usually ease discomfort, and as injury begins to health the anxiety starts to subside
Chronic pain-Pain lasting for longer than six months
-Even if condition expected to be acute pain, but with no resolution ; 27% men and 31% women
-Can be intermittent or constant, mild or severe, depending on its type; most types the diseases process is primarily responsible for pain
experienced, but psychosocial factors may play role
-Suffers who report higher level of satisfaction with social support exhibit higher level of pain-related behaviours
-Sleep disturbance irritated by little things and trivial comments, realize this but can’t seem to stop lead to social withdrawal
-Living standards is reduced because 59% have to leave their jobs, if compensation received for pain experience (ex. Job injury) than may
exacerbate perceived severity of pain and distress
Pain behaviours -Alternations in behaviour by a person experiencing pain to either reduce pain or prevent it from getting worse
-Can reinforce behaviours if pain behaviours appear successful at preventing or reducing pain, will continue for fear pain will return if not
resistant to change (these behaviours)
Pain threshold -Point at which the intensity of a stimulus is perceived as painful
Cold pressor task-Determine pain threshold; submerge hand in cold water until they experience pain, indicate when by pushing a button
Pain tolerance (level) -Duration of time or intensity at which a person is willing to endure a stimulus beyond the point where it began to hurt “can’t stand it anymore
Pain catastrophizing -Exaggerated negative orientation towards noxious stimuli; spend considerable time ruminating about aspects of pain experienced become
fearful of pain and adopt a form of helplessness
-High communicate pain more effectively when an observer is present + experience fewer cognitive coping strategies and perceive more
intense pain in others
Autonomic activity-Consciously uncontrollable physiological processes, such as heart rate, respiration ate, blood pressure, hand surface temperature, skin
-Instrument that assess pain by measuring electrical activity in brain
-Evoked potentials: electrical responses produced by stimuli; increase with intensity of stimuli and decrease when people take analgesics
-stimuli detected by sensory system can produce evoked potentials or change in EEG voltage
Behavioural assessment:
day-to-day activities
-pain behaviour; how much time spend in bed, complaints, seek help in moving,
-family or significant others best to make these assessments trained + make accurate records
Behavioural assessment
of pain behaviour in
clinical settings
-health care professionals in general underestimate patient’s pain under treatment of pain
-procedures available to assess pain hospital nurses my use UAB pain behaviour scale during routine care = nurse and patient perform
several activities and rates ten pain behaviours on scale
Box scale-scale which people rate and report their pain by choosing number that best indicates degree of pain they are experiencing from a series of
numbers in boxes ranger from no pain to worst pain imaginable”
Verbal descriptor scale-rating scale where asked to describe pain by choosing phrase that most closely resembles the pain that they are experiencing
Visual analog scale-rating scale on which people report their pain by marking a point on a line anchored by the phrase no pain and by a phrase like worst pain
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