Plan
► Concept of pain, classification of pain.
► History of concept of pain.
► Modern concepts of sensory nociceptive system:
• characteristics of receptor part of nociceptive system;
• characteristics of conducting part of nociceptive system;
• central part of nociceptive system.
► Concept of antinociceptive system; structural and functional organization, interrelation with nociceptive system.
► Modern concept of pain.
Concept of Pain. Classification of Pain
Pain is of a great significance in physiology, pathophysiology and in all fields of medicine. Understanding of physiological bases of pain permits to gain a deeper insight into the interactions of an organism with different internal and external stimuli including those leading to damage of tissues. Besides, knowing mechanisms of pain, a physician can timely and adequately use various medical means to improve the condition of a patient.
Pain is a physiological phenomenon that informs us of hazardous influences which damage or potentially threaten an organism. Thus, pain is both a warning and protecting event.
Currently the most popular is definition of pain given by the International Association for Study of Pain: ?Pain is an unpleasant sensory and emotional experience associated with actual or potential damage to tissue or described in terms of such damage.?
There are two main kinds of pain: physical pain and psychogenic pain. By cause, physical pain is classified into three categories.
► Pain caused by external factors (except for pain caused by excessive adequate stimulations of sensory organs, for example, of vision, of audition).
Such pain is characterized by the following features: it is superficial, brief except for the cases associated with breakage of the integrity of skin. Such pain can be easily localized and its cause identified. The external factor can be eliminated. The nervous system remains undamaged, its peripheral apparatus and central mechanisms remain intact.