The causes and conditions of occurrence of disorders of the nervous system − Rakyat Biologi

Pathogenic factors that cause damage to the nervous system, are exogenous or endogenous nature. Exogenous factors may be pathogenic neurotropic, certain structures affecting the nervous system, ie specific. Non-specific etiological factors damaging not only nervous, but also other tissues. Exogenous factors affecting the nervous system, are biological pathogens: viruses (rabies, polio), microbes (leprosy), plant toxins (strychnine, curare), microbial toxins (botulinum, tetanus), alcohols (ethanol, methanol), pesticides (trichlorfon), chemical agents, etc.. Specific for human pathogenic factor is the word. It can cause disturbances of mental activity, behavior, disorders of various functions on the conditional reflex mechanism.

Endogenous pathogenic factors are divided into primary and secondary. The primary concern hereditary disorders of genetic and chromosomal neurons devices. They are linked hereditary diseases of the nervous system (Down syndrome, endogenous psychosis, etc.), Circulatory disorders in a variety of CNS, ischemia, and others.

The secondary endogenous pathogenic effects include destruction of internal organs and systems, when neural tissue is involved in the pathological process in the course of the underlying disease (hepatic encephalopathy, uremic coma, diabetic neuropathy, and coma, etc.).

Etiologic factors cause changes in the nervous system. The latter play the role of pathogenic factors: changes in neurons, violation of separation and reception of neurotransmitters, acquired alterations in the genome of neurons, changes interneuronal relations nervous trophism, the formation of antibodies to the nerve tissue, disruption of antisystems (analgesic, anticonvulsant, and others.). Typical pathogenic changes may be the formation of aggregates of hyperactive neurons, which are generators of pathologically enhanced excitation (GPEE), the formation of pathological determinants of pathological systems and pathological dominants.

Understanding the pathogenesis and knowledge of the pathological process development mechanisms required for adequate pathogenetic therapy. So, it is useless to treat tetanus toxin induced CNS only tetanus toxoid, tetanus toxin neutralization, as the latter has already contacted the nerve elements and caused corresponding changes in the central nervous system (in particular, damage to the proteins involved in the selection of brake transmitters). Treatment at this stage should be aimed at eliminating the consequences of the action of tetanus toxin (suppression of neuronal hyperactivity, struggle with seizures, etc.). The use of tetanus toxoid in this step is necessary for the neutralization of new portions of tetanus toxin, tetanus produced in the wound rod.

Realization of the pathogenic effects depends on their strength and duration - the stronger and more enduring these effects, the greater its effect. However, even a weak pathogen exposure, if they are long and persistent, can cause deep and lasting changes in the nervous system. For example, if the fractional, repeated administration of neurotropic toxins (tetanus, botulinum, etc.) Of the total dose, causing a pathological effect and the death of the animal, can be less than that which causes a similar effect with a single administration of the entire dose of the toxin (Bering phenomenon). Daily electrical stimulation of brain structures subthreshold current strength is not accompanied by a visible reaction, it leads to the increase of convulsive readiness of the brain. With the passage of time on the same subliminal exposure to the animal responds already cramps (the phenomenon of "swing" or kindling). In everyday life, there are many long-term stressors, nevrozogennye factors, occupational hazards, etc.

Factors that do not cause disease initially normal nervous system can acquire pathogenic significance for the nervous system, altered previous pathological processes with genetically determined predisposition, hyperexcitability, etc. Limbic structures, particularly the hippocampus, more others are able to develop and maintain a pathological overactivity that It can be caused by even a single pathogenic effects.

An important role in maintaining the pathological effects of playing the plasticity of the nervous system - the ability to consolidate the changes arising. This feature provides the ability of its development, the formation of new relationships, learning, structural rearrangements, etc. However, plasticity - Blind force, it establishes not only a biologically useful, but also pathological changes. Due to the plasticity caused fixed structural and functional abnormalities in the nervous system (e.g., synaptic disturbances generated excitation generators, and other pathological system.). Since plasticity linked in many cases, chronicity of the pathological process and its resistance to therapeutic effects.

Pathogenic changes in the nervous system are the two kinds of phenomena. The first of them - the damage and destruction of the morphological structure, functional relationships and physiological systems. It is indicated by IP Pavlov as "damage" and is the result of the direct action of the pathogenic agent. Another phenomenon is the appearance of new, abnormal integration of modified neural structures.

The very "damage" is not the development of the pathological process. He plays the role of the causes and conditions of this development, which is carried out its own endogenous mechanisms of nervous system damage.

At the level of relations interneuronal such integration is a unit of hyperactive neurons at the level of intercellular relationships - a new organization consisting of altered CNS departments - pathological system. Thus, the actual pathogenesis of neurological disorders characterized not only by the destruction, but also the emergence of pathological formations - the unit and pathological neuronal systems, ie is the destruction of physiological and pathological formation systems.