The international association for study of pain defines pain as an unpleasant sensory & emotional experience associated with actual or potential tissue damage.
Its purpose is to allow the body to react and prevent further tissue damage. The experience of pain is different for everyone, and there are different ways of feeling and describing pain. This can makes it difficult to define and treat. Pain is just not a physical sensation. It is influenced by attitudes, beliefs personality & social factors & can affect emotional & mental well being. Although two people may have the identical pain condition, their experience of living with pain can be vastly different.
Pain is subjective and difficult to quantify, because it has both an affective and a sensory component. Although the neuroanatomic basis of pain reception develops before birth, individual pain responses are learned in early childhood and are affected by social, cultural, psychological, cognitive, and genetic factors, among others. Those factors account for differences in pain tolerance among humans. Athletes, for example, may be able to withstand or ignore pain while engaged in a sport, and certain religious practices may require participants to endure pain that seems intolerable to most people. Quite often people report pain in absence of any tissue damage or any likely patho-physiological cause, usually this happens for psychological reason.
Pain is felt when special nerves that detect tissue damage send signals to transmit information about the damage along the spinal cord to the brain. These nerves are known as nociceptors. The brain then decides what to do about the pain.
For example, if you touch a hot surface, a message will travel through a reflex arc in the spinal cord and cause an immediate contraction of the muscles. This contraction will pull your hand away from the hot surface. This happens so fast that the message doesn't even reach the brain. However, the pain message will continue to the brain. Once there, it will cause an unpleasant sensation of pain to be felt.
How an individual's brain interprets these signals and the efficiency of the communication channel between the nociceptors and the brain dictate how people feel pain.
The brain may also release feel-good chemicals such as dopamine to counter the unpleasant effects of the pain.
Severe pain from an injury or other stimulus, if continued over some period, was found to alter the neurochemistry of the central nervous system, thereby sensitizing it and giving rise to neuronal changes that endure after the initial stimulus is removed. That process is perceived as chronic pain by the affected individual. Pain perception and response differ with gender andethnicity and with learning and experience. Women appear to suffer pain more often and with greater emotional stress than do men, but some evidence shows that women may cope with severe pain more effectively than men.