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How the Body Transmits and Responds to Pain

Updated on April 30, 2009

Most people do not enjoy pain, but it serves an important purpose, in that pain is our bodies way of telling us something is not right.

This pain usually goes away as the body heals or with the help of medication. This sharp pain is referred to as acute pain and is caused by the nervous system, however sometimes the pain doesn't go away.

This type of pain is called chronic pain or persistent pain. Chronic pain can have a very big impact on all aspects of an individuals life. The effects of this type of pain are sometimes referred to as the terrible triad, which includes suffering, sadness, and sleeplessness.

Due to a better understanding of how pain works and its effect on the body, doctors are today better able to treat and deal with both chronic and acute pain.


Not too long ago, doctors had thought that pain was caused when a persons nerve endings where pressed very hard, which is to an extent true. However, pain is actually caused by the response of a special type of nerve fiber.

The pain nerve fibers are called nociceptors and are positioned throughout the body. Nociceptors are only activated by intense and potentially harmful situations. Nociceptors can be stimulated by a number of situations and not all are sensitive to the same types of sensations.

For example, some nociceptors will respond to a forceful blow, such as when you are using a hammer and missing the nail, hitting your thumb instead. Others might be sensitive to heat, while ignoring the sensation of a needle or pinprick. These nociceptors are scattered throughout the body, to ensure that the proper signals are sent to the brain.

Transmitting the Pain Signal

The signal sent from the nociceptors is processed quickly and broadcast to a number of different parts of the body. For instance, if you were to put your hand down on a hot stove, the pain signal will be sent to your muscles, which instinctively contract to remove your hand from the stove.

The pain signal almost instantly initiates one of the bodies natural reflexes, which is a protective reaction, but the signal also travels to your brain, informing you of the incident.

The signals help inform the brain how bad the damage is and where it occurred. The pain signal also travels throughout other parts of the body, informing other nerve fibers that there was an accident. The body in turn takes steps to help deal with the damage, like increased blood rate and heavy breathing. Together, these signals all help contribute to what is referred to as the suffering component of pain, which can include fear, anxiety, and anger.

Not only does the pain signal help raise the alarm, but it also initiates a number of natural reactions to deal with the cause of the pain, such as releasing hormones like adrenaline or dilating the eyes pupils.

The Pain Gate Theory

Of course, as is often the case, the body sometimes ignores the pain signals. Perhaps a person might cut themselves while working very hard and not realize it or perhaps a basketball player might continue playing despite suffering from a torn ligament.

Scientists during the nineteen sixties put forth a theory referred to as the the pain gate theory, which address how the pain signal is sent and why it is not always triggered.

The theory stated that when an event occurred, such as a cut, pain signals amassed until they reached a certain point, at which time the pain gate opened informing the rest of the body. This idea helped to explain how you might be able to pick a scab or touch a sprained ankle.

A Discovery About Neurotransmitters

The idea of the pain gate caused a great deal of controversy as it was not completely accepted. However, it was later discovered that the body can release a special pain blocking chemical.

While trying to determine how medicines like morphine and other opiates worked, a team of doctors made some very interesting observations of how neurotransmitters transferred pain to one another.

They knew from previous research that chemicals played a role in transmitting signals between two cells and observed that a special chemical neurotransmitter that would form, extending from the cell. The neurotransmitter would then make contact with a special receptor on another cell, allowing for the pain signal to be transmitted.

In some instances the neurotransmitter would excite the cell, causing it to create its own neurotransmitter, while other times it would not. In the case of morphine, the doctors discovered that the opiate actually positioned itself on the receptor of certain cells in the brain and spine, effectively blocking the neurotransmitter.

They hypothesized that a similar process occurred naturally in the body to block out pain.

A Natural Painkiller

The research into the effects of morphine, led researchers to identify a number of pain blocking proteins that were produced naturally by the human body. They called these proteins endorphins, which means “morphine within.”

The discovery of endorphins helped to add more weight to the gate theory, because doctors hypothesized that these endorphins might be released when an individual rubbed an arthritic joint. This hypothesis was confirmed, when doctors discovered that endorphins were released as a result of painful stimulation.

Armed with the knowledge of how endorphins worked and the bodies own natural pain suppression techniques, doctors were able to reevaluate current pain fighting techniques.


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