Nociception is a sense which allows people to experience pain; the term comes from the roots for “noxious” or “unpleasant” and “sensation.” While people do not usually enjoy painful stimuli, being aware of pain can be very important, as it alerts the body to the fact that a situation is dangerous, or to an existing problem which needs to be addressed. In certain individuals, nociception can be impaired, and this can lead to very serious problems because they fail to interpret painful stimuli when they are exposed to them.
This sense is achieved with a network of specialized nerves called nociceptors. Nociceptors occur in great abundance just under the skin, and they are also found inside the body, everywhere from the organs to the joints, so that they can transmit information about painful experiences to the brain. When these nerves are exposed to unpleasant stimuli, such as heat, cold, or cutting sensations, they send a message to the brain indicating that something unpleasant is going on.
The brain often reacts by trying to avoid the painful situation, as when someone flinches when cut by a knife as the body responds to the pain. It can also trigger the secretion of analgesics which will reduce the pain. People become aware of the brain as the body responds to it, so that they can make conscious decisions which could end up reducing or ending the pain. For example, visceral pain could indicate a problem with one of the abdominal organs, and by going to the doctor, the issue could be addressed.
Nociceptors in the body are less widely distributed, because the precise pain reception observed on the surface of the skin is not as critical in the body. The brain lacks nociceptors altogether, which researchers believe is due to the fact that circumstances which could cause pain in the brain could also presumably be fatal, making nociception rather pointless.
The process of nociception can be blocked with medications, as is done when people take pain management medications or are put under general anesthesia for a surgical procedures. Some people are born without nociception, which might sound rather nice to anyone nursing an injury, but can actually be extremely dangerous. Without the ability to receive noxious stimuli, people may not be aware that they are being injured by something such as a burn or a cut, and they can develop very severe injuries or even die as a result of their lack of sensitivity to pain.