Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm. Individuals experience pain by various daily hurts and aches, and occasionally through more serious injuries or illnesses. For scientific and clinical purposes, pain is defined by the International Association for the Study of Pain (IASP) as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage". Pain is part of the body's defense system, triggering a reflex reaction to retract from a painful stimulus, and helps adjust behavior to increase avoidance of that particular harmful situation in the future. Given its significance, physical pain is also linked to various cultural, religious, philosophical, or social issues.
The word “pain” does not equate with nociception, which is a preconscious neural activity that is normally necessary, but not sufficient, for pain. The term nociception was coined by Charles Scott Sherrington to make clear the difference between the physiological nature of nervous activity signalling tissue damage and the psychological response of pain to this physiological event. In animal, we have to speak of “nociceptive transmission” instead of... [more]
Pain, in the sense of physical pain, is a typical sensory experience that may be described as the unpleasant awareness of a noxious stimulus or bodily harm. Individuals experience pain by various daily hurts and aches, and occasionally through more serious injuries or illnesses. For scientific and clinical purposes, pain is defined by the International Association for the Study of Pain (IASP) as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage". Pain is part of the body's defense system, triggering a reflex reaction to retract from a painful stimulus, and helps adjust behavior to increase avoidance of that particular harmful situation in the future. Given its significance, physical pain is also linked to various cultural, religious, philosophical, or social issues.
The word “pain” does not equate with nociception, which is a preconscious neural activity that is normally necessary, but not sufficient, for pain. The term nociception was coined by Charles Scott Sherrington to make clear the difference between the physiological nature of nervous activity signalling tissue damage and the psychological response of pain to this physiological event. In animal, we have to speak of “nociceptive transmission” instead of “pain transmission” since pain per se cannot be communicated by animals. Nociception is the afferent activity produced in the peripheral and central nervous system by stimuli that have the potential to damage tissue. This activity is initiated by nociceptors that can detect mechanical, thermal or chemical changes, above a certain threshold. All nociceptors are free nerve endings of fast-conducting myelinated A delta fibers or slow-conducting unmyelinated C fibers, respectively responsible for fast, localized, sharp pain and slow, poorly-localized, dull pain. Once stimulated, the nociceptors transmit signals that travel along the spinal cord and within the brain. Brain areas that are particularly studied in relation with pain include the somatosensory cortex which mostly accounts for the sensory discriminative dimension of pain, and the limbic system, of which the thalamus and the anterior cingulate cortex are said to be especially involved in the affective dimension. Nociception, even in the absence of pain, may trigger withdrawal reflexes and a variety of autonomic responses. The control of nociceptive transmission is complex and involves numerous peripheral and central mechanisms.
In its pathological manifestation, pain is a major symptom in many medical conditions, significantly interfering with a person's quality of life and general functioning. Diagnosis is based on characterizing pain in various ways, according to duration, intensity, type (dull, burning or stabbing), source, or location in body.
Among the most frequent technical terms for referring to abnormal perturbations in pain experience, there are: allodynia (pain due to a stimulus which does not normally provoke pain), hyperalgesia (an increased response to a stimulus which is normally painful) and hypoalgesia (diminished pain in response to a normally painful stimulus). As an example, allodynia is a clinical feature of many painful conditions, such as neuropathies, postherpetic neuralgia, fibromyalgia, and migraine.
Usually pain stops without treatment or responds to simple measures such as resting or taking an analgesic, and it is then called ‘acute’ pain. But it may also become intractable and develop into a condition called chronic pain, in which pain is no longer considered a symptom but an illness by itself.
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PAIN
