Pain is difficult to define as it is subjective and psychological. Probably the best definition is that it is an unpleasant experience associated with the tissue damage.
Pain is more complex than other sensory systems such as vision or hearing as it involves transfer of sensory information to the nervous system but produces suffering which leads to aversive corrective behaviour like withdrawing from harmful agents. Thus it serves as a useful warning system.
Pain receptors in the skin and other tissues of our body are nerve terminals which are triggered by a chemical stimulus when a potential damage occurs. Acute pain often has simple and effective treatment regimes. However, chronic pain rarely has simple solutions as it is not fully understood. It is inevitably accompanied by many psychological factors such as depression, anxiety and personal environmental interactions.
An indirect or inferential measurement of some one’s pain may be made by means of so-called pain thresholds. There are many methods available for measuring this threshold which however are open to criticism.
A popular method is to employ a dolorimeter which uses a heat source operated by a timing mechanism. An even safer device is a pressure algometer, a rod with a flat end loaded against a calibrated spring. Pressure applied on a flat body surface (for example, the skin) is increased steadily until pain is reported. Under controlled conditions women are more sensitive to pain (have lower thresholds) than men, office workers than manual workers, and anxious people than calm people.
There are a number of reports of people without the ability to feel pain at all or in some cases very little. They are at a greater risk of suffering and their life expectancy is shorter than average.
