ABSTRACT
Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. The biological processes involved in our perception of pain are no longer viewed as a simple ‘hardwired’ system with a pure ‘stimulus–response’ relationship. The more recent conceptualization of pain seeks to take into account the changes that occur within the nervous system following any prolonged, noxious stimulus. Nociception describes the somatosensory response of the nervous system to a potentially harmful stimulus and serves to avoid tissue damage. The functions of nociceptors include transducing noxious stimuli to depolarizations that trigger action potentials, converting action potentials to release neurotransmitters at the presynaptic terminal and conducting the action potentials to synapses in the central nervous system. Nociceptors are widespread in skin, muscle, connective tissues, blood vessels and thoracic and abdominal viscera.
