Noxious stimuli, response

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. 

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... 

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... 

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. 

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. 

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

This sensory mismatch is interpreted as a noxious stimulus and initiates a physiological response similar to that to substances perceived as poisonous, and a number of autonomic nervous system responses are activated to reject the perceived poison. 

Pain can be described as a complex experience consisting of aphysiological response to a noxious stimulus followed by an affective (emotional) response to that event. Pain, in the context of a homeostatic mechanism, is a warning signal that helps to protect an organism by influencing it to withdraw from harmful stimuli it is primarily associated with injury, or the threat of injury, to the body tissue. 

Facial movement to command or in response to noxious stimulus (nasal tickle)... 

The diseases mentioned are considered to be host defense mechanisms. Inflammation Is a normal and essential response to any noxious stimulus that threatens the host and may vary from a localized response to a generalized response (6). The resulting inflammation can be summarized as follows 1) Initial injury causing release ... 

Hyperalgesia Exaggerated response to a mildly noxious stimulus applied to the affected region... 

Figure 7 Schematic diagram illustrating the central role of the keratinocyte in skin inflammation. In response to an external noxious stimulus (e.g., chemical, physical, or mechanical), the keratinocyte produces a vast array of chemical mediators, including the proinflammatory cytokines. These mediators initiate a cascade of cellular events in their target cells. More details on cytokine function can be found in Table 11. (After Ref. 190 with permission.)...

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