The antinociceptive system of the human body is a clearly defined structure of nerve endings located in all areas and in all parts of the central nervous system. Their combination has a peculiar hierarchy of active neurochemical levers that have the ability to suspend the functionality of pain structures that are part of the nociceptive system.
The action of the antinociceptive system
When the pain system is used, as a rule, an opiotergic regulatory scheme. It consists in the interaction of opiate receptors with opioid ligands. Mediators of the antinociceptive system are able to suppress uncomfortable intolerable sensations at various levels. Thanks to the work of this mechanism, pain and discomfort did not become the predominant feeling in human life. Even when the pain occurs, the active elements of the antinociceptive system are included in the work, which can be felt at the moment of the pain retreat, pause. This is the main function of this protective mechanism in the body of any person.
The Importance of Narcotic Painkillers Today
Interest in narcotic substances, by the way, also gave rise to the antinociceptive system. The physiology of the human body clearly outlined the purpose of narcotic substances in medicine: they are used as the strongest anesthetic drug that can help the antinociceptive system overcome pain or act as a substitute for it.
To date, narcotic substances are the only option for effective symptomatic treatment of cancer patients. This may well justify the use of drugs, given their analgesic effect. However, everyone knows the main minus of such drugs: they are able to turn an adequate, mentally stable person into a dependent creature, experiencing unearthly torment and, probably, ending its life path prematurely.
Differences between nociceptive and antinociceptive systems
The antinociceptive system is a pain determinant that guarantees 100% pain perception. Considering this term, the differences between this concept and the term "sensory system" can be determined without difficulty. Since the fundamental accepted “device”, that is, the defining analyzer, can be called only a separate fragment of the sensory system, the nociceptive and antinociceptive systems in total are not just a determinant, but a rather complex self-governing somatic system.
To understand what this means, you need to give an example. Medical practice knows rare cases of a lack of pain in a person who is congenital. Meanwhile, the main nociceptive pathways work as usual for them, that is, the mechanism for preventing pain activity is functioning.
How does pain and pain shock appear ?
By the 70s of the last century, scientific researchers had finally formed an opinion about such a component of the central nervous system as the antinociceptive system of the brain. At that time, scientists were able to establish its ability to limit pain excitation, prevention of overstrain of structures of the nociceptive department. The increasing irritation in the nociceptive system provokes active inhibition of this process by anti-pain elements.
Pain shock can occur only when, with excessive exposure to the body of the antinociceptive system, it is not possible to suppress the strength of the influence of extraneous factors. A decrease in inhibitory function is fraught with overexcitation of the nociceptive system and the generation of unforeseen unexpected pains of a psychogenic nature in absolutely normal unaffected organs.
The structure of the analgesic system of the body
Considering the concept of antinociception (antinociceptive system), attention should be paid to its individual components. Among them, first of all, it is worth noting the elements of the spinal cord, midbrain and medulla oblongata (gray matter, the nucleus of the reticular formation and the nucleus of the suture, the gelatinous component of the spinal cord).
Thanks to them, the main blocking of pain occurs. A person ceases to feel pain when a stream of nociceptive excitement directed upward is amenable to oppression. This function belongs to the downward control of pain. The main active ingredients in inhibitory work are opioids and some hormones, for example, serotonin. It is more correct to call them modulators, since they change the initial position of the final neurons, while not transmitting any exciting effect in their direction.
Mediators and receptors of pain in the anticyceptive system
The main and predetermining neurons of the analgesic system are those that are located in the gray matter of the midbrain. Important here is the role of axons, which are ascending paths to the hypothalamus and other mechanisms of the left hemisphere of the brain. They also participate in the opposite direction to the spinal cord. The mediators of these neurons are pentapeptides, which include subspecies of enkephalins. Such mediators in the form of amino acids should receive methionine and leucine.
Enkephalins are able to excite all opiate receptors in a fairly short time. In opiatergic synapses, such receptors are located mainly on the membrane, which performs the tasks of the postsynaptic “pillow”. Synapses that were not involved in the process become painful, then mediators should be released through the membrane, directing the uncomfortable excitation from a particular neuron to another.
The endogenous antinociceptive system has characteristic opiate receptors, which are more metabotropic. They are often associated with a bioregulator that causes inhibition of adenylate cyclase through intracellular recognition. The consequence of all of the above is a violation in the process of synthesis of the pain system. In addition to the pathological reduction of calcium intake in the human body, the main mediators of the pain syndrome are included, that is, the body begins to produce them independently. The most common pain mediators are:
- substances P;
- cholecystokinin;
- somatostatin;
- glutamic acid.
Hypothalamus and left brain - activators
The structure of the anti-pain system includes the analgesic structures of the hypothalamus and somatosensory region of the cortex of the left cerebral hemisphere. The limitlessness of their inhibitory effect on human nociceptive mechanisms is achieved due to:
- downward inhibition of the effect on spinal cord neurons;
- upward inhibition of the effect on the neurons of the thalamus;
- increased impact on the above system of downward control of the brakes.
Self-management of pain in the body
The nociceptive and antinociceptive systems of the body are in direct coordination. The latter produces opioid endogenous components, which in fact are drugs within us.
These include endorphins, dynorphins, etc. A feature of their chemical composition is steep peptide sequences, like tiny protein molecules that consist of amino acids.
The role of opioid and non-opioid peptides
On the predominant number of neurons, which includes the antinociceptive system, special receptors for such substances are located. For example, upon contact of the receptors with opioids, subsequent inhibition often appears at the level of individual neurons. In this case, the nociceptive pain system becomes inhibited and practically does not respond to pain. The task of small neurons of the analgesic system is to create obstacles to the transmission and distribution of pain stimulation along the chain of subsequent endings.
Not only opioid peptides are involved in the regulatory process of the occurrence of pain. Non-opioid peptides (e.g., neurotensin) also have an effect on the overall pain perception of a person. Arising from a variety of sources, pain can inhibit noadrenaline, dopamine, serotonin and other catecholamines.
How does the pain suppression mechanism work?
The antinociceptive system of the body can function in several ways:
- The mechanism of urgent action. A pain stimulus reaction occurs, as a result of which synapses are excited in the downward brake control system. Within the posterior horns of the spinal cord at this time, one can observe the limitation of afferent nociceptive excitation. This mechanism is involved in the main analgesia. When pain is suppressed, two pain stimuli act simultaneously.
- The mechanism of short action. The launch is performed by the hypothalamus, involving systems of inhibitory control of the descending type of the spinal, middle and medulla oblongata. To activate the mechanism to limit pain excitation at the level of the spinal cord, and sometimes the brain, stressful factors are needed.
- The mechanism of prolonged action. The main centers are located in the hypothalamus, are activated with constant pain. An upward flow of pain stimulation is transmitted in all areas of the downward control. The emotional coloration of pain is connected to the nociceptive system. Such an assessment in most cases is not objective.
- Tonic mechanism. Thanks to him, the constant activity of the antinociceptive system is supported by the centers of the orbital and frontal zones of the cerebral cortex. They are located in the frontal lobe, behind the eyes. The activity of the nociceptive structure is provided by a constant inhibitory effect. By the way, this process can be noticed with the complete absence of pain.
What is the pain?
The body's antinociceptive system, which controls the structures of the cerebral cortex, helps to prepare for the painful effect, and then take a pain irritant with a decrease in unpleasant, uncomfortable sensations.
From all of the above, one can draw a simple conclusion that the intensity and nature of pain are determined by the features of the functioning of two systems: nociceptive and antinociceptive. The first is pain, the second is anti-pain. The specificity of their interaction determines the nature of the pain experienced by a person. The pain can be different, namely:
- Hyperalgesia is a condition with increased sensitivity to pain, the result of which may be either a high excitation of the nociceptive system, or a low excitation of the antinociceptive system.
- Hypoalgesia is a condition with reduced sensitivity to pain, resulting from the opposite effect: the antinociceptive pain system rises, and the excitation of the nociceptive system decreases.
Both conditions can have a positive value for the body, while they largely depend on the threshold of pain. This value is a non-static moving indicator that varies with the characteristics of the pain and analgesic systems. Both antinociceptive and nociceptive structures form a single complex of pain, being only its elements.
What threatens a person with pain?
A sufficiently complex sensory system of pain perception is necessary for a person to maintain the body and its individual parts in integrity. In addition, disorders of the functions of these systems (pain and anti-pain) affect human life in the most negative way. With acute short or chronic pain, the following occurs:
- Sleep disturbances.
- Lack of sex drive.
- Irritability, carelessness.
- Decreased motor activity.
- Depression, oppressed psycho-emotional state.
Pain Shock - Fatal
Intense pain can slow down breathing, sometimes even stop it completely, while weak background pain can affect its speed. With severe pain, the heart rate increases, blood pressure rises, which threatens the development of a spasm of peripheral blood vessels.
At first, the skin becomes pale, but with short-term pain, dilated vessels cause hyperemia. Salivation decreases, the production of juices of the stomach and pancreas, intestinal motility stops, which often leads to anuria. The development of pain shock with severe pain is fatal.