Pain is the greatest evolutionary mechanism that allows a person to notice danger in time and respond to it. Pain receptors are special cells that are responsible for receiving information and then transmitting it to the brain in the pain center. You can read more about where these nerve cells are located and how they work in this article.
Pain
Pain is an unpleasant sensation that is transmitted to our brain by neurons. Discomfort appears for a reason: it signals actual or potential damage in the body. For example, if you bring your hand too close to the fire, a he althy person will immediately pull it back. This is a powerful defense mechanism that instantly signals possible or ongoing problems and forces us to do everything to fix them. Pain is often indicative of a specific injury or injury, but it can also be chronic,exhausting character. In some people, pain receptors are hypersensitive, as a result of which they develop a fear of any touch, as they cause discomfort.
Knowing the principle of action of nociceptors in a he althy body is necessary in order to understand what the pain syndrome is associated with, how to treat it, and also what causes excessive sensitivity of neurons. The World He alth Organization has now recognized that no human being should endure pain of any kind. There are many drugs on the market that can completely stop or significantly reduce pain even in cancer patients.
Why is pain needed?
Most often, pain occurs due to injury or illness. What happens in the body when, for example, we touch a sharp object? At this time, receptors located on the surface of our skin recognize excessive stimulation. We do not yet feel pain, although the signal about it is already rushing through the synapses to the brain. Having received the message, the brain gives a signal to act, and we withdraw our hand. This whole complex mechanism takes literally thousandths of a second, because a person's life depends on the reaction speed.
Pain receptors on the hairline are located literally everywhere, and this allows the skin to remain extremely sensitive and sensitive to the slightest discomfort. Nociceptors are able to respond to the intensity of sensations, temperature rise, as well as various chemical changes. Sothe expression "pain is only in your head" is true, since it is the brain that creates unpleasant sensations that make a person avoid danger.
Nociceptors
The pain receptor is a special type of nerve cell that is responsible for receiving and transmitting signals about various stimulations, which are then transmitted to the central nervous system. The receptors release chemicals called neurotransmitters that travel at great speed through the nerves, the spinal cord, to the human's main "computer" in the pain center. The whole process of signaling is called nociception, and pain receptors, which are located in most known tissues, are called nociceptors.
Mechanism of action of nociceptors
How do pain receptors in the brain work? They are activated in response to some kind of stimulation, be it internal or external. An example of external stimulation is a sharp pin that you accidentally touched with your finger. Internal stimulation can be caused by nociceptors located in internal organs or bones, such as osteochondrosis or curvature of the spine.
Nociceptors are membrane proteins that recognize two types of effects on the neuron membrane: physical and chemical. When human tissues are damaged, the receptors are activated, which leads to the opening of cation channels. As a result, sensory neurons fire, and a pain signal is sent to the brain. Depending on what kind of effect is exerted on the tissue, differentchemical substances. The brain processes them and chooses a “strategy” to follow. In addition, pain receptors not only receive a signal and transmit it to the brain, but also release biologically active compounds. They dilate blood vessels, help attract cells of the immune system, which, in turn, help the body recover faster.
Where they are located
The human nervous system permeates the entire body from the fingertips to the abdomen. It allows you to feel and control the whole body, is responsible for the coordination and transmission of signals from the brain to various organs. This complex mechanism also includes notification of injury or any damage, which begins with pain receptors. They are located in almost all nerve endings, although they are most often found in the skin, muscles and joints. They are also common in connective tissues and in internal organs. On one square centimeter of human skin, there are from 100 to 200 neurons that have the ability to respond to changes in the environment. Sometimes this amazing ability of the human body brings a lot of problems, but mostly it helps to save a life. Although at times we wish we could be free from pain and not feel anything, this sensitivity is essential for survival.
Pain receptors in the skin are perhaps the most common. However, nociceptors can be found even in the teeth and periosteum. In a he althy body, any pain is a signal of some kind of malfunction, and itshould never be ignored.
Difference in nerve types
The science that studies the process of pain and its mechanisms is quite difficult to understand. However, if we take knowledge of the nervous system as a basis, then everything can be much simpler. The peripheral nervous system is the key to the human body. It goes beyond the brain and spinal cord, so with the help of it a person cannot think or breathe. But it serves as an excellent "sensor", which is able to catch the smallest changes both inside the body and outside. It consists of cranial, spinal and afferent nerves. It is the afferent nerves that are located in tissues and organs and transmit a signal to the brain about their condition. There are several types of afferent nociceptors in tissues: A-delta and C-sensory fibers.
A-delta fibers are covered with a kind of smooth protective screen, so they transmit pain impulses the fastest. They respond to acute and well-localized pain that requires immediate action. Such pain can include burns, wounds, trauma and other injuries. Most often, A-delta fibers are located in soft tissues and muscles.
C-sensory pain fibers, on the contrary, are activated in response to non-intense, but long-term pain stimuli that do not have a clear localization. They are not myelinated (not covered with a smooth membrane) and therefore transmit a signal to the brain somewhat more slowly. Most often, these combat fibers react to damage to internal organs.
Travel signalpain
Once a noxious stimulus is transmitted along the afferent fibers, it must pass through the dorsal horn of the spinal cord. This is a kind of repeater that sorts the signals and transmits them to the appropriate sections of the brain. Some pain stimuli are transmitted directly to the thalamus or brain, allowing for a quick response in the form of action. Others are sent to the frontal cortex for further processing. It is in the frontal cortex that the conscious realization of the pain we feel occurs. Because of this mechanism, during emergency situations, we do not even have time to feel discomfort in the first seconds. For example, with a burn, the most severe pain occurs after a few minutes.
Brain response
The last step in the pain signaling process is the response from the brain, which tells the body how to respond. These impulses are transmitted along the efferent cranial nerves. During pain signaling, a variety of chemicals are released in the brain and spinal cord that either decrease or increase the perception of pain stimuli. They are called neurochemical mediators. They contain endorphins, which are natural analgesics, as well as serotonin and norepinephrine, which increase the perception of pain by a person.
Types of pain receptors
Nociceptors are divided into several types, each of which is sensitive to only one type of irritation.
- Receptors for temperature and chemical stimuli. The receptor responsible forperception of these stimuli has been named TRPV1. It began to be studied in the 20th century in order to obtain a medicine that can relieve pain. TRPV1 plays a role in cancer, respiratory disease and more.
- Purine receptors respond to tissue damage. At the same time, ATP molecules enter the intercellular space, which in turn affect purinergic receptors that trigger a painful stimulus.
- Acid receptors. Many cells have acid-sensitive ion channels that can respond to various chemicals.
The variety of types of pain receptors allows you to quickly send a signal to the brain about the most dangerous damage and produce the appropriate chemical compounds.
Types of pain
Why do things hurt so much sometimes? How to get rid of pain? Humanity has been asking these questions for several centuries and finally found the answer. There are several types of pain - acute and chronic. Acute often occurs due to tissue damage, for example, when a bone is broken. It can also be associated with headaches (which most of humanity suffers from). Acute pain goes away as quickly as it comes - usually as soon as the source of the pain (such as a broken tooth) is removed.
Chronic pain is a bit more complicated. Doctors still cannot completely rid their patients of chronic injuries that have been bothering them for many years. Chronic pain is usually associated with long-term illness, unidentifiedcauses, cancer or degenerative diseases. One of the main contributing factors to chronic pain is an unknown cause. In patients who experience pain for a long time, depression is often observed, and pain receptors are modified. The chemical reaction of the body is also disturbed. Therefore, doctors do their best to find the source of the pain, and if this is not possible, they prescribe painkillers.
Painkillers
Painkillers, or painkillers, as they are sometimes called, usually work with the help of neurochemical mediators. If the drug inhibits the release of "second messengers", then the pain receptors are simply not activated, as a result of which the signal does not reach the brain. The same thing happens if the reaction of the brain in response to the stimulus is neutralized. In most cases, painkillers can only temporarily affect the situation, but cannot cure the underlying problem. All they can do is keep the person from feeling the pain associated with a chronic illness or injury.
Results
Pain receptors in the hairline, lymph and blood allow the human body to quickly respond to external stimuli: changes in temperature, pressure, chemical acids and tissue damage. The information activates nociceptors, which send signals along the peripheral nervous system to the brain. That, in turn, immediately reacts and sends a return impulse. As a result, we withdraw our hand from the fire beforeWe have time to realize this, which can significantly reduce the degree of damage. Pain receptors have, perhaps, such an effect on us in emergency situations.
