Mechanisms in the organism that can detect temperature differences or pain, for example, are important for humans and other living creatures. These sensory perceptions are detected and transmitted by nerve fibers that, in addition to those in the skin, are also present in blood vessels and sweat glands. Each person’s perception of pain is different. Thus, when pain occurs, interactions between the psyche and perception occur. Pain perception is therefore a very complex process that is triggered by receptors in the nervous system and interpreted and processed in the central nervous system.
What is the sensation of pain?
Each person’s perception of pain is different. Thus, interactions between the psyche and perception occur when pain occurs. The perception of pain is determined by psychological, physical, and social factors that interact with each other. In this context, pain is primarily a purely subjective perception that is not determined solely by the signals transmitted via the nerve fibers and pathways. In medicine, pain is divided into two categories. On the one hand, it can occur as a symptom, and on the other hand, as a symptom of disease progression, in which case it can also occur as chronic pain. In order for a person to feel pain, the organism needs its free nerve endings to respond to stimuli. Such stimuli can be different, triggered by temperature, pressure, inflammation or injury. Pain receptors so designated need a very strong trigger to become excited. To activate the receptors, substances are needed that change. These are called pain mediators and include serotonin, bradykinin or prostaglandins. Due to the increased excitation during irritation, the ph value decreases and the tissue is supplied with less oxygen. This changes the electrolyte balance in the blood. This is why pain often accompanies injury and disease.
Function and task
First and foremost, however, pain is important for the organism because it shows it that something is wrong, normal functions are impaired in the process and damage can occur. This type of acute pain is necessary, can be quickly identified in the cause and eliminated. Chronic pain, on the other hand, lasts longer and is detached from the actual disease. It is therefore still present, although a signal effect in the body via the receptors no longer takes place. For example, injury to tissue causes the release of various endogenous substances, including oxygen radicals, potassium ions, arachidonic acid, protons and ATP. An enzyme is formed that converts arachidonic acid, which has formed in the membrane of a damaged cell, into prostaglandid E2. The same process is started in the conversion of kinins into bradykinin. In this process, degranulation occurs. Inflammatory mediators cause dilation of blood vessels. Nociception is the result. Nerve fibers transmit pain signals in the organism and are divided into A-delta and C-fibers. The latter are older in the sense of the development history and lower in the transmission speed. In this process, escape movements can occur, which take place due to reflex circuits in the spinal cord, but which have not yet been consciously perceived. A well-known example is the hand on a hotplate. This already jerks back before the person has recognized that the plate is hot. On the other hand, the signals are also transmitted to the brain via the “tractus spinothalamicus“. The sensation of pain is then triggered in the cortex and evaluated in the limbic system as recognized information. Influences on the perception of pain include the descending antioziceptive pathways, which alter sensitivity. The body reacts to pain by releasing endorphins, which reduce the sensation of pain. Because pain has the function of a warning signal for the body, it is also called nociceptor pain. Distinct from this is neuropathic pain, which responds directly to damage in the body, including infection or amputation.
Diseases and complaints
Since pain perception is always subjective, misunderstandings and general problems of understanding regarding the intensity of the pain and the disease may occur between doctor and patient.The organism is very adaptive in this respect, which means that pain that occurs repeatedly triggers longer and also more intense pain sensations, since the pain threshold, i.e. the strength of the stimulus and the transmission of the resulting signals, is automatically lowered in the body. Medicine refers to this as pain memory, which is associated with chronic pain. Along with the actual pain sensations, other symptoms also occur that change a person’s life in this respect. Thus, among other things, sleep disorders, depression and anxiety can be the result, which cannot always be eliminated by simple drug treatment and yet are related to the pain. Disturbances in the organism that are of a functional nature can also cause pain, for example, if certain subsystems are functioning incorrectly. Circulatory disturbances in the brain lead to migraine, influences such as fear, stress or disgust cause a different kind of pain. The sensation of pain is divided here into an affective and sensory one, with the affective form being felt subjectively and described with words such as “excruciating” or “violent”, whereas sensory effects are more likely to occur than the actual perception and are then described with words such as “burning” or “drilling”. To better diagnose pain, it is assessed by where it occurs, in what form, with what impact and cause, in what degree of pain, and under what circumstances. Therapies are then carried out with treatment, through medication, massage, immobilization of the affected body parts and fractures, physiotherapy, or surgery to remove the affected tissue, organ or body part. There are also methods to measure the degree of pain. Statistics and pain scales are established via self-reporting by affected individuals. If communication is not possible, as in infants or young children, a scale based on observing five characteristics is used. These are facial expression, crying, trunk and leg posture, and agitation.
