Your body's mechanisms for reacting to pain are complex and happen at lightning speed. The experience of pain sends millions of people to their health-care providers or to the analgesic section of the drug store. There's much to be learned about the body's pain response and equally much to be learned about what science and medicine are doing to try and alleviate pain.
The health-care community has a saying about a person's pain, "Pain is what you say it is." This might sound trite, but the truth is that pain is a subjective symptom. If you feel throbbing pain in your lower back, then that is exactly how it is for you. Another person with exactly the same set of circumstances as to the cause of your pain may experience it at a different level---and for that person, that's exactly how the pain is to him.
Some astonishing statistics reveal just how pain impacts your daily life: 4 billion work days lost; 40 millions doctor visits for "new" pain; $3 billion spent on over-the-counter analgesics (Bio-Medicine).
The manner and extent to which you experience pain at any time is not only affected by the painful stimulus itself, but by any number of factors, including emotional, biological, and even lifestyle factors.
The chain of reactions that occur in the body when pain occurs are rapid-fire, channeled through the nervous system as quickly as electricity flows through power lines. The nervous system is your body's "wiring." The nervous system is thought of in two parts: the central nervous system which is the brain and spinal cord, and the peripheral nervous system which is comprised of all the offshoots of nerve fibers that go throughout the body.
Peripheral Nervous System
These peripheral nerve fibers end in pain receipting endings called nociceptors, of which there are millions throughout your body. Areas of the body that are more prone to injury, such as the skin, have more nociceptors than underlying tissues such as muscle or bone.
When a pain stimulus is sensed by the nociceptors, signals from the area are sent to the spinal cord. These nerve endings send their messages in a manner that is proportional to the perceived threat---that is, dull pain is sent via slower connections to the spinal cord than is sharp pain.
When the spinal cord receives a signal, its first function is to determine what sort of threat to your body is the stimulus. If there is a perceived imminent threat of damage, the spinal cord puts that message quickly through to the brain. Other signals from less threatening stimuli such as a paper cut get sent more slowly to the brain.
It's in the spinal cord that messages to other nerve cells tell your body to react by quickly moving away from the stimulus, such as touching your fingertip to a hot iron. Your reflex is to pull away immediately; this is the spinal cord's method of reducing injury to your body.
The nerve cells in the spinal cord can also sense other types of messages from the peripheral nervous system and slow down/eliminate sending pain signals to the brain from a region, such as when an aching muscle is massaged.
When the pain signal from the spinal cord nerves reach the brain, it is first processed by the thalamus. From the thalamus, the pain signal then is transferred to the limbic system (emotional response center) and the cerebral cortex (thought center and automatic response center).
Depending on the extent of the damage that the pain signal indicates to these two centers, the other systems of the body such as the blood system will be sent automatic signals to minimize damage and begin repair---the work of the cerebral cortex. The cerebral cortex also is responsible for messages such as better positioning of a body part to decrease pain.
It is the cerebral cortex which is responsible for the release of the chemicals known as endorphins, which help to alleviate the pain.
Meanwhile, your limbic system is reacting simultaneously to the painful occurrence, causing an emotional reaction. As children we may cry or be frightened when pain occurs. As adults, we might cry out momentarily or simply be stoic---it is here that your emotional conditioning as a child and as an adult come into play.
Medical research is ongoing in many areas, and pain reduction is no exception. The more scientists are able to understand the complex mechanisms of how the body reacts to pain, the better they are able to develop medications and technology to alleviate pain.
Studies being done by the University of California, Irvine, and the University of Georgia on rats have discovered a chemical produced by the brain when stress-related pain occurs that is one of the substances in cannabis, called 2-AG (BBC News). This research is yet in its early stages, but scientists think this discovery may eventually lead to improved types of pain medications.
Professor Danielle Piomelli, director of the research team at the University of California, Irvine, stated, "This study shows for the first time that natural marijuana-like chemicals in the brain have a link to pain suppression" (BBC News).
Research being conducted at the University of California, San Francisco, and the University of Minnesota suggest that 2 particular peptides may be a factor in pain suppression. Thus far the scientists have been working with mice; their research indicates that the substances they've isolated do, in fact, have something to do with your body's response to pain (Bio-Medicine).
What this, and other ongoing research will mean for you in the future is difficult to determine at this point, but science and the health-care community are working towards better control and alleviation of your pain.