[Pain--physiological or medical phenomenon]

The word "pain" is ambiguous, symbolic and it is understood differently by the patient and by the doctor or physiologist. It describes a kind of sensation evoked by harmful stimuli which is a physiological phenomenon indispensable for protection and also suffering caused by injury or disease. The second component of the phenomenon is usually not recognized--this is the reaction to pain. The primary component is centripetal and ascending to brain centers, the second is centrifugal, descending and they both form the reflex arc. This is the pain or nociceptive reflex. Commonly, when we speak of pain we mean only the centripetal part of the reflex which cannot be objectively assessed in medical practise. This part is blocked by anaesthesia before surgical procedures. The second part is the subject of a separate consideration which begins with psychic reaction to pain and pain tolerance, and suffering depend on it. The motor reaction to pain is more spectacular and possible for recording. Three types of this reaction are discerned: flight, defense and suffering expression. Nociceptive sensation is a physiological receptor-mediated sensation, while pathological pain can derive from receptors as well as from nerves /conduction pain, neuropathic differentiation pain/ or from centres/central pain. The pathological pain has clinical features making possible the recognition of its origin, its mechanism for undertaking of appropriate measures. Neuropathic pain is the one most difficult to treat. The receptor-mediated pain continues as long as the stimulus is active, the neuropathic pain is longer lasting.