Perseverative Cognition
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P-30 Antigen ▶ Prostate-Specific Antigen (PSA)
in response to injury, to chronic states in which pain persists beyond the point of tissue repair or healing. Although the Gate Control Theory (Melzack & Wall, 1967) provides a unified model of pain, a variety of pain subtypes exist that have different underlying mechanisms.
Pain Michael James Coons1 and Jeremy Steglitz2 1 Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA 2 Department of Psychiatry and Behavioral Sciences, Clinical Psychology Division, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
Synonyms Pain management/control; Pain: psychosocial aspects; Pain threshold
Definition Pain is a noxious sensory phenomenon that provides information to organisms about the occurrence or threat of injury. Pain is also a multidimensional experience that results from a complex interaction between biological and psychological components and is further influenced by behavioral and social factors. The temporal course of pain can range from acute, or time-limited states
Description Neurobiology of Pain A primary function of the nervous system is to communicate information to alert organisms to the experience or threat of injury. Therefore, the noxious qualities of pain function to capture our attention and motivate action to minimize the risk of harm. Nociceptors are a specialized class of primary afferent nerves. Myelinated nociceptors signal sharp pain from heat and pressure stimuli on skin with hair. Unmyelinated nociceptors signal burning and pressure-induced pain on hairless skin. Both unmyleinated and myelinated nociceptors signal pain from chemical stimuli. Injury leads to increased pain sensitivity or hyperalgesia caused by inflammation. CNS Mechanisms of Pain Modulation
At the level of the spinal cord, pain modulation occurs in the substantia gelatinosa (SG) of the dorsal horn. The SG serves an inhibitory or gating function that modulates pain signal transduction. Pain modulation also occurs in the periaqueductal gray (PAG) and rostral ventromedial medulla (RVM) of the midbrain, which
M.D. Gellman & J.R. Turner (eds.), Encyclopedia of Behavioral Medicine, DOI 10.1007/978-1-4419-1005-9, # Springer Science+Business Media New York 2013
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function as a bidirectional relay station. The system is involved in the suppression of ascending responses to harmful stimuli and enhances nociceptive responses. The PAG-RVM system has connections to the hypothalamus and limbic forebrain structures including the amygdala, anterior cingulate cortex, and anterior insula. Consequently, fear, attention, and pain expectancies exert top-down processes that influence pain perception. Clinical Classifications of Pain Postoperative Pain and its Management Acute postoperative pain is a product of a range of physiological mechanisms. It comprises a constellation of sensory, emotional, and psychological experiences that follow surgery and is associated with autonomic, endocrine-metabolic, physiological, and beha
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