Few people can boast that they have never experienced pain. She, like a shadow, is constantly next to a person from birth to the last minute of life. It signals about malfunctions in organs and tissues, in a special and usually unpleasant way for a person, in a way it informs about a hidden danger, about developing ailments.
But often pain takes on such terrible forms that from an invisible controller of the state of our body, it turns into a ruthless and merciless enemy. And then a person's life turns into a nightmare, his psyche, seized by painful anxiety, breaks down.
Of course, this all-encompassing phenomenon of the body could not be ignored by pundits. The first who tried to explain such a concept as "pain" was Aristotle. When the great thinker described the five human senses - sight, hearing, taste, smell, touch - he left pain outside this list, believing that it is a special "passion of the soul" caused by other feelings.
And Aristotle's views on the essence of pain dominated the minds of scientists until the 17th century. It was only in 1644 that the French scientist Rene Descartes tried to change this point of view to the phenomenon of pain: after numerous and detailed experiments, he suggested the presence of a special pain channel connecting the skin to the brain.
And although after the research of the famous Frenchman, hundreds of scientists in different countries of the world were studying pain, a clear understanding and even definition of this sensation has not appeared.
However, today it is indisputable that pain is a subjective phenomenon. Its strength and intensity largely depend on the person's personality, his psychological and physical condition, age, social environment in which he lives, and upbringing.
Each person perceives and expresses pain very individually, and the sensitivity to pain is different for different people. It can be very high or too low.
Promotional video:
Moreover, there are known cases of absolute insensitivity to pain. Usually people with certain mental disorders do not respond to pain. In addition, this rare disease is usually accompanied by pathological changes in other sensory organs: for example, touch, taste. In this case, a person who does not respond to pain signals, for example, drinks boiling water like cold water.
The causes of pain can be very different: burns, cuts, bruises. In addition, many organic and inorganic substances, both in the surrounding world and synthesized by the cells of the organism itself, can cause unbearable pain. For example, compounds formed during reactions of tissue metabolism, or substances involved in the regulation of the functions of certain organs.
One of these pain-relieving compounds is histamine. It turned out that in acute and chronic diseases, the amount of histamine in the blood increases several times. Especially a lot of it with neuralgia, migraine, angina pectoris, myocardial infarction.
The human body is very sensitive to this substance. Even at a concentration of 0.000000000000000001 g / l, which corresponds to 54 molecules per 1 million, histamine causes pain.
In addition to histamine, some other substances can also cause pain: adrenaline, acetylcholine, serotonin, potassium and calcium salts. Not the last place in this series is occupied by kinins - substances contained in the blood and tissues of the body.
They are absent in a healthy person. Instead, their inactive forms, kininogens, circulate through the blood. The kinins themselves begin to exist at the moment when the body is injured. And, in order to protect itself from blood loss, it turns on the most complex defense mechanism - the blood coagulation system. It was then under the influence of the so-called Hageman factor, from kininogens and kinins themselves are formed.
In 1931, biochemists discovered another unknown compound that causes pain in the gastrointestinal tract and human brain: substance "P". Especially a lot of it was found in the central nervous system and spinal cord.
Of course, histamine, kinins, and substance “P” by themselves cannot cause pain. They only signal about malfunctions in the body. It is generally accepted that pain-relieving substances block the delivery of oxygen to the tissues and thereby suppress their respiration. Figuratively speaking, pain is a "scream" of suffocating cells and tissues.
This signal of help is immediately captured by the chemoreceptors, which, concentrating around the blood vessels, are two "lines of warning" in the body's defense system: cutaneous and visceral. The skin line begins to function with damage to the external tissues, and the visceral line - with diseases of the internal organs and the vascular system.
The received signal of a possible threat through nerve fibers called nociceptors is immediately transmitted to the brain center - the thalamus. In the thalamus, the information received is first sorted, and then enters other parts of the brain, where the final formation of pain sensations and their conscious assessment takes place.
And since pain, depending on its duration, can be acute or chronic, there are two types of fibers for its conduction in the nervous system: fast-reacting pain fibers and slow chronic pain fibers.
When the brain receives a signal about tissue or organ damage, the pituitary gland, the endocrine gland located at the base of the brain, is turned on. It synthesizes special substances - endomorphins, the chemical structure of which is similar to that of morphine and a number of other analgesic compounds.
Endomorphins immediately "bind" to certain receptors in the brain cells, activating them, and these, in turn, send signals that suppress pain. But when the pain continues for a long time, then processes occur in the human brain that prevent the production of endomorphins.
According to statistics, about 65% of humanity suffers from pains of varying intensity. Therefore, the problem of stopping or at least partially relieving the pain syndrome worries and has always worried doctors.
To reduce pain in medicine, a variety of drugs are used, mainly non-narcotic analgesics. They have no side effects such as addiction, lethargy or increased irritability. In terms of chemical structure, they most often belong to the group of opium alkaloids or are their analogs obtained in laboratory conditions.
PARADOXES OF PAIN SENSITIVITY
In addition to the fact that pain itself is constantly in the center of attention of many scientists, there are also some of its extremes that are of particular interest to specialists. For example, hypersensitivity to the most seemingly insignificant irritations. Indeed, doctors sometimes have to deal with situations where a seemingly insignificant effect on the skin or some organ causes a person's excruciating pain that does not fade for a long time.
In this case, hypersensitivity can touch a particular area of the body, and it can be fixed on the entire skin, as well as on mucous areas. This increased sensitivity of the body to pain is called hyperalgesia.
People who suffer from this disease have to avoid any, even the smallest physical contact with the outside world, since any touch of their skin causes painful reactions in them. For example, wearing clothes becomes almost torture for them. They perceive temperature effects especially painfully.
So, if an ordinary person, having dipped his hand into water with a temperature of 35 to 45 ° C, feels warmth, then a patient with hyperalgesia experiences severe, unbearable pain resembling a burn. He feels the same when the water is cooled down to - 10-15 ° С.
Moreover, such patients sometimes feel severe pain even when the object does not touch the surface of the skin, but is at a distance from it.
It is believed that the cause of such reactions of the body to external influences is the pathology of skin receptors and sensory nerve fibers, or disorders in certain areas of the brain or spinal cord.
However, clinicians even know cases when some patients, it would seem, in the absence of objective reasons, nevertheless, have unbearable pain. Usually they are suspicious people, prone to exaggeration and fantasy …
However, in addition to being hypersensitive to pain, doctors also know exactly the opposite examples, that is, when people very weakly, or even did not react at all to painful stimuli. Such reactions of the body to pain are called hypoalgesia and are usually observed in certain mental illnesses, in particular hysteria.
People suffering from this disease practically do not react to burns, injuries, wounds. Their skin can be cut, cauterized, and pricked, but most often they will only experience a light touch.
In one of the patients suffering from this disease, a group of small cells was noted in the posterior horns of his spinal cord. Scientists have not established the cause of this anomaly: either it was a congenital defect in the nervous system, or it appeared as a result of some kind of disease.
An interesting example of hypoalgesia is given by G. N. Kassil in The Science of Pain, published in 1975 by the Science Publishing House. The author writes:
“During World War II, a 25-year-old corporal approached the US Air Force Medical Commission with complaints of complete insensitivity to pain. A young man appeared before the commission, looking quite healthy and full of strength. Upon questioning, it turned out that in early childhood he had undergone surgery for some kind of ear disease. From about eight years old, he began to suffer from strange seizures, during which, according to the testimony of others, he lost consciousness.
The corporal assured the commission that during his entire adult life he had never felt pain. He did not experience pain when drilling teeth with a drill, with subcutaneous and intramuscular injections, with cuts, etc. Several times after prolonged vaccinations against typhus and tetanus, his arm swelled, but he never experienced any pain. Finally, when he was deeply wounded in the lower leg with an ax in 1939, there was no pain despite the gaping wound.
The corporal claimed, and his parents confirmed it, that neither beatings nor illness caused him pain. He never suffered from seasickness, never felt an itch after an insect bite. Under the conditions of the front, the corporal could easily endure the heat and cold and could not imagine what a headache meant.
The medical board was extremely interested in their patient. He was subjected to a comprehensive examination, and in the end the doctors came to the conclusion that in front of them was not a simulator trying to free himself from military service, but really a person who was not familiar with the feeling of pain.
Using the thermal method for determining the threshold value of various pain sensations, the doctors found that even with very intense heating of the skin of the forehead, back and hands, the "patient" feels only moderate warmth and, in some cases, slight tingling, while his comrades experienced acute pain.
The patient did not complain of muscle pain during prolonged muscle contractions, did not feel pain in the nasopharynx when inflating a rubber balloon inserted into the esophagus, etc. It should be remembered that all these manipulations cause severe pain in healthy people.
When the hand was immersed in ice-cold water, the amazing patient felt "chill", but did not feel pain, like his comrades. The introduction of histamine into the blood caused his face reddening, heart palpitations, a feeling of warmth, but by no means a headache, as is the case in all people.
After long and sometimes very unpleasant studies, the commission came to the conclusion that the patient had disturbances in the activity of the central nervous system. Apparently, after the operation, he developed some changes in the cerebral cortex or in the visual hillocks, which led to a loss of pain sensitivity.
The patient did not know what pain was, his central nervous system did not perceive pain signals, and not a single doctor in the world could cure him of his peculiar disease - the absence of pain”…
In the same book, the author gives two more examples of hypoalgesia.
“In 1965, one of the French journals published the story of a 62-year-old patient MB, who was admitted to the Neurosurgical Hospital of Buenos Aires with seizures of general seizures.
Examining the patient, the doctors noticed that he had no corneal and pharyngeal reflexes at all. Later it turned out that the patient had no pain sensitivity on the entire surface of the skin. Painful irritations - injections, burns - did not cause him either a feeling of pain or any noticeable defensive reaction.
Even the slightest changes in cardiac activity, respiration, blood pressure could not be noted. There were also no pupillary reactions. Pain sensitivity remained only in the scrotum area, and even then it was significantly reduced. Some manipulations, usually very painful (such as blowing air into the ventricles of the brain, examining the bladder), did not cause any discomfort in this patient.
The most interesting results were obtained with histological examination of the skin. It turned out that the skin (with the exception of the scrotum) lacked free nerve endings, which, as indicated, are pain receptors.
Melzak describes an interesting case of complete insensitivity to pain. A young educated girl, well versed in her feelings, was examined in detail by doctors of various specialties. It turned out that she often bites her tongue, burned herself several times and never experienced pain. Electric current, hot objects or ice applied to the skin did not cause any discomfort.
At the same time, the blood pressure did not rise, the pulse did not increase, and the respiration did not change. Reflexes (pharyngeal, corneal) were absent. The histamine injection was completely painless. At the age of 29, the patient died from a severe infection, but (which is especially interesting), shortly before her death, she began to complain of soreness in the lumbar region, which, however, quickly passed under the influence of analgin."
In total, about 20 cases have been described in the literature when people from infancy did not have any reactions to pain. True, they reacted to especially strong stimuli with defensive-defensive movements, the release of adrenaline, etc.
Unfortunately, scientists do not yet know the mechanisms that turn off pain sensitivity in humans. But the fact that indifference to pain affects the entire body suggests that this phenomenon is associated with the nervous system.
Sometimes there is another rather rare pathology - the absence of any reaction to a painful stimulus. And although a person suffering from this disease feels pain, sometimes quite excruciating, nevertheless, he does not react to it at all. It turned out that patients with this syndrome have serious pathologies in the frontal and parietal regions of the brain.