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Understanding Pain
Pain is the means by which the Peripheral Nervous System (PNS) warns the Central Nervous System (CNS) of injury or potential injury to the body. The CNS is composed of the brain and spinal cord, whereas the PNS includes all nerves throughout the body except the brain and spinal cord.
Pain originates when a signal is transmitted to the CNS by special nerve cells called nociceptors. These nerve cells are located throughout the body and respond to different stimuli depending on their location. When a nociceptor is stimulated, chemical messages, called neurotransmitters, are released within the cell. The nociceptor transmits its signal to nerve cells within the spinal cord, which conveys the pain message to the thalamus, the region in the brain responsible for receiving pain impulses.
Upon receiving this signal, the brain releases its own natural pain killers called endorphins that are meant to reduce or stop pain messages from the source. However, these natural pain killers will not sufficiently dampen a continuing pain message, or one that is too strong. Following some disorders or physical injury, pain does not resolve. Even after healing the brain continues to perceive pain. In this situation, the pain is considered to be chronic. Physicians consider a pain that endures beyond a normal healing time to be chronic.
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