Noxious stimuli

The sensation of pain, following injury or disease, in response to a previously non-noxious stimulus is termed allodynia . Tactile allodynia is caused by... 

Increased responsiveness to noxious stimuli is termed hyperalgesia. It occurs following injury or disease and encompasses enhanced responses as well as reduced thresholds to a given noxious stimulus. Primary hyperalgesia occurs in the damaged area whereas secondary hyperalgesia occurs in the area surrounding it. 

Pain production is the most common injury inflicted on man. This noxious stimulus is perceived almost instantly after skin - tentacle contact. A subpopulation (30 - 40%) of visceral sensory C fibers denoting noscioception have been shown to be selectively excited experimentally in nerve ganglia preparations by a component of... 

Sensory detection of a noxious stimulus is known as nociception 928 Primary sensory neurons sense pain and convey it to the spinal cord 928... 

Sensory detection of a noxious stimulus is known as nociception. The perception of such a stimulus, nociceptive pain, is essentially the ouch pain we experience in response to a pinprick or touching a hot or very cold object. Nociceptive pain is an important physiological... 

Clinical pain is characterized by the presence of spontaneous pain or hypersensitivity to pain-provoking stimuli. Hypersensitivity includes pain produced by low-intensity stimuli that normally only elicit an innocuous sensation (allodynia), or an exaggerated response to a noxious stimulus (hyperalgesia). There are two distinct forms of clinical pain, the pain that occurs after tissue injury or inflammatory diseases (inflammatory pain) and the pain associated with a lesion or disease of the nervous system (neuropathic pain). Although the mechanisms responsible for the initiation and maintenance of these pains differ, they are both characterized by heightened... 

The sensation of the noxious stimulus occurring within the brain. 

Inflammation is a local and early response of a tissue to a noxious stimulus, such as physical injury or infection. It results in an increase in the number of immune cells in the area of damage or infection which kill pathogens, remove damaged or dead cells and initiate the healing process. The well-known characteristics of inflammation are redness, heat, swelling and pain. Redness is due to increased blood flow to the damaged area caused by vasodilation of small arterioles, which facilitates an increase in the number of immune cells in the damaged area and facilitates provision... 

MAC is the anesthetic concentration that produces immobility in 50% of patients exposed to a noxious stimulus. 

The dose of anesthetic gas that is being administered can be stated in multiples of MAC. A dose of 1 MAC of any anesthetic prevents movement in response to surgical incision in 50% of patients however, individual patients may require 0.5-1.5 MAC. Unfortunately, MAC gives no information about the slope of the dose-response curve. In general, however, the dose-response relationship for inhaled anesthetics is very steep. Therefore, over 95% of patients may fail to respond to a noxious stimulus at 1.1 MAC. 

Because the CPA test is based on associative learning between a noxious stimulus-induced aversive affect and a neutral environmental context, it is difficult to determine whether the attenuation of CPA is due to the impairment of associative learning or the suppression of the primary aversive affect. To address this issue, we examined whether intra-vBNST injection of isoproterenol, a /3-adrenoceptor agonist, produced CPA even in the absence of formalin-induced noxious stimulus. The results showed the aversive effect of intra-vBNST injection of isoproterenol, indicating that the activation of /3-adrenoceptors within the vBNST is sufficient to produce the negative affective states. Therefore, the attenuation of F-CPA and A-CPA by the blockade of /3-adrenoceptors within the vBNST may be due to the reduction of the primary aversive affect. 

Prevention of purposeful movements response to a noxious stimulus. The animals are stimulated for 60 s by placement of a 1-kg weight on the middle of the tail. Only the purposeful movement of the head or legs is considered to be a response. 

Prevention of the heart rate increase to a noxious stimulus (ECG signals). An increase in heart rate of greater than 1 % is regarded as a positive response. 

Allodynia pain that is elicited by a non-noxious stimulus—such as the touch of clothing, air movement, or a light touch of the hand—or pain when something mildly cool or warm touches the skin. 

Hyperpathia delayed and explosive pain response to a noxious stimulus this is indicative of sensitization of pain fibers in the CNS. 

Acute pain can be described as sharp or dull, burning, shock-like, tingling, shooting, radiating, fluctuating in intensity, varying in location, and occurring in a timely relationship with an obvious noxious stimulus. Chronic pain can present similarly, and often occurs without a timely relationship with a noxious stimulus. 

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