General pathogenesis: term, definition of the concept. Damage as the initial link in pathogenesis. Levels of damage and their manifestations. General concepts of etiology, pathology, pathogenesis, pathological processes and symptoms - abstract

I
(pathogenesis; Greek pathos suffering, disease + genesis origin, origin)
a set of processes that determine the occurrence, course and outcome of diseases. The term “pathogenesis” also refers to the study of the mechanisms of disease development and pathological processes. In this doctrine, a distinction is made between general and particular P. The subject of general P. is the general patterns inherent in the main features of any disease process or individual categories of diseases (hereditary, infectious, endocrine, etc.). Particular P. studies the mechanisms of development of specific nosological forms. General P.'s ideas are formed on the basis of the study and generalization of data on the mechanisms of development of individual diseases, as well as on the basis of the theoretical development of philosophical and methodological problems of general pathology and medicine in general. At the same time, the doctrine of general P. is used in the study and interpretation of the mechanisms of development of individual specific diseases and the characteristics of their course.
The study of P.'s disease is based on the analysis of clinical data, the results of a variety of laboratory, electrophysiological, optical, radiological, morphological and many other research methods, including various functional tests and mathematical processing methods. Of great importance for the study of both the general patterns of P. diseases and the mechanisms individual diseases and pathological processes have various forms of modeling pathology on living and non-living objects, as well as mathematical and cybernetic modeling.
significantly depends on etiological factors. In some cases, the action of the etiological factor throughout the entire disease process decisively determines its P. (for example, in most infectious diseases, many intoxications, hereditary diseases, some endocrine disorders). In other cases, the primary impact of the etiological factor is only a trigger in the chain of cause and effect. Each link in this chain becomes, in turn, an etiological factor in the natural development of subsequent phenomena, i.e. pathogenesis of the disease process, even in the absence of its root cause. In some cases, P. is characterized by the appearance of a so-called vicious circle. Thus, hypoxia of any origin (for example, circulatory), having reached a certain degree, leads to disruption of other parts of the oxygen transport and utilization system (for example, respiratory center). The resulting alveolar hypoventilation aggravates the severity of the hypoxic state, which, in turn, causes further hemodynamic disorders, deepening hypoxia, even greater respiratory failure. The specific structure of the vicious circle may be different, but once it occurs, it usually seriously aggravates the course of the disease process, often creating life-threatening situations. The resulting vicious circle is often eliminated only with external intervention.
The nature and significance of etiological factors in the development of the disease at its different stages can change many times. Due to the presence of a dialectical relationship between the categories of etiology and pathogenesis in medical literature The term “etiopathogenesis” appeared, but it was not widely used.
The ratio and significance of local and general processes in P. is variable. Thus, with inflammation (Inflammation) caused by local tissue damage, the pathological process develops mainly in the area of ​​damage and is aimed at limiting the source of alteration, destroying or removing the damaging factor, products of cell destruction and compensation of the local tissue defect. General changes in the body are in most cases relatively minor. In other cases, small-scale local disorders through the receptor apparatus and neurogenic mechanisms or through the humoral route (as a result of a lack or excess of biologically active substances) cause pronounced generalized reactions. Examples of this include gallstones and kidney stones, pulpitis - limited inflammatory process, which, as a result of strong painful stimulation, entails a whole chain of reactions. Generalization of local processes may be associated with physiological significance damaged structures responsible for vital important functions body, such as the respiratory center or the conduction system of the heart. Along with this, local pathological changes in various organs and systems can arise secondary as a result of primary generalized processes (for example, kidney damage during general intoxications). The area of ​​secondary local damage depends on many factors: the specific tropism of pathogenic agents to certain tissues, the routes of their elimination, biological features damaged structures. Individual morphofunctional features organism, depending on its constitution (Constitution), previously past diseases and other factors that determine the reactivity of the body and its reactive properties individual organs, fabrics and systems.
With the development of any disease, as a rule, nonspecific and specific P mechanisms are detected. Nonspecific mechanisms are typical pathological processes, for example, inflammation, fever, thrombosis, as well as so-called elementary processes, for example, increased permeability of biological membranes, changes in membrane potential, generation active forms oxygen, etc. An example of specific mechanisms is the activation of cellular and humoral immunity, hormone receptor interactions. However, an alternative distinction between P.'s mechanisms into specific and nonspecific cannot be carried out consistently. Thus, inflammation and fever in each specific case may have a number of characteristic distinctive features, and at the same time highly specific immune processes contain a number of common features.
Among the various mechanisms of disease development, the most significant ones are identified, which are constantly encountered in a given disease and determine its main features. These mechanisms are usually called the main links of pathogenesis. Such a basic link, for example for acute blood loss in initial stage, is a decrease in circulating blood volume and circulatory hypoxia. For more late stages, after replenishing the blood volume due to tissue fluid and renal water retention, the leading element of P. becomes hemodilution, accompanied by hypoproteinemia and hemic hypoxia. After restoration of blood proteins, hemodilution erythropenia remains the main element of the posthemorrhagic state for some time. Thus, as the disease process develops, the leading links of P. may change. It often turns out to be impossible to single out from many pathogenetic factors a single one - the main or leading one, even taking into account the stage of the disease.
The occurrence, development and completion of a disease in the vast majority of cases consist of processes that are dual in their biological essence and significance for the body. P. includes a direct consequence of the action of a pathogenic factor (primary damage or disorder), which arises secondarily during the disease process, structurally functional disorders and simultaneously or with a certain shift in time, developing protective-adaptive (sanogenetic) reactions aimed at preventing or eliminating pathogenic effects and disorders that have arisen in the body. The triggering mechanisms for these reactions can be the pathogenic factor itself, as well as the primary and secondary results of its damaging effects. Both primary and secondary violations, and protective adaptive reactions can be realized at various levels - from molecular to organismal, including behavioral reactions.
When assessing individual components of P., a discrepancy often arises between their potential and actual value for the body. For example, the most important process that is protective in nature - inflammation, under certain conditions, can have harmful and even harmful effects on the body. disastrous consequences. The real meaning of individual elements of inflammation - venous hyperemia, increased permeability - may also be different. blood vessels, exudation, etc. In some cases, the same reaction to the influence of a pathogenic factor simultaneously has both positive and negative meaning. So, spasm of the adductor arterioles renal glomeruli at acute blood loss helps maintain central hemodynamics and water retention in the body. However, at the same time it has a biologically negative meaning, because disrupts excretory function; in addition, intense and prolonged ischemia of the renal glomeruli can lead to their degeneration and severe renal failure.
Bibliography: Ado A.D. Questions of general nosology, M., 1985; Anokhin P.K. Essays on Physiology functional systems. M., 1975; Davydovsky I.V. General pathology Cheloveka, M., 1969; Methodological problems of medicine and biology, ed. D.K. Belyaev and Yu.I. Borodina, Novosibirsk, 1985; General human pathology, ed. A.I. Strukova et al., book. 1-2, M., 1990; Petlenko V.P. Philosophical questions of the theory of pathology, book. 1-2, L., 1968-1971; Petlenko V.P., Strukov A.I. and Khmelnitsky O.K. Determinism and the theory of causality in pathology, M., 1978; Tsaregorodtsev G.I. and Petrov S.V. The problem of causality in modern medicine. M., 1972.
II
(pathogenesis; Patho- + Greek genesis origin, development)
1) the doctrine of the general patterns of development of the course and outcome of diseases;
2) the mechanism of development of a specific disease, pathological process or condition.

View value Pathogenesis in other dictionaries

Pathogenesis- and IS, pathogenesis, pl. no, m. (from the Greek pathos - disease and genesis - birth) (med.). Sequence in development of some. pathological (painful) process. typhoid fever.
Ushakov's Explanatory Dictionary

Pathogenesis of M.— 1. Features of the occurrence and development of the disease process or disease in general. 2. Clarification of the peculiarities of the occurrence and development of the disease process or the disease in general.
Explanatory Dictionary by Efremova

Pathogenesis- [né], -a; m. [from Greek. pathos - suffering, illness and genesis - origin, occurrence] Honey. The sequence of occurrence and development of a disease process or disease........
Kuznetsov's Explanatory Dictionary

Pathogenesis— (pathogenesis; patho- + Greek genesis origin, development) 1) the doctrine of the general patterns of development of the course and outcome of diseases; 2) the mechanism of development of a specific disease, pathological........
Large medical dictionary

Pathogenesis- (from the Greek pathos - suffering - disease and ... genesis), mechanisms of development of diseases and pathological processes (for example, inflammation).
Large encyclopedic dictionary

Pathogenesis- (Greek pathos - disease, genesis - origin, development). 1. The doctrine of general principles, patterns of development, course and outcome of diseases (study of inherent diseases........
Psychological Encyclopedia

What is pathogenesis, types of pathogenesis.

Pathogenesis is a complex of processes that determine the occurrence, course of a disease and its completion. The term "pathogenesis" is also used to define the science that studies the mechanism of development various diseases and pathological processes resulting from damage to various organs and systems.

Types of pathogenesis.

There are general and specific pathogenesis. General pathogenesis studies general changes in the body, arising in any pathological process, as well as developmental features separate groups diseases, for example, processes in the human body are studied during endocrine disorders, with hereditary pathologies or infectious lesions. Specific pathogenesis studies the mechanism of development of individual nosoological units, i.e. processes in the human body during a certain disease are studied. General and specific pathogenesis are interrelated. Knowledge of general pathogenesis is accumulated through the study of individual diseases, and the study of specific pathogenesis is impossible without theoretical basis, which is included in the general pathogenesis.

What does pathogenesis study?

Pathogenesis studies all the changes that occur in the body after exposure to a causative factor. When studying pathogenesis, the following criteria are taken into account:

1. The role in the development of the disease of the factor that leads to this lesion, i.e. it is necessary to determine the role of the etiological factor. Thus, the etiological factor can only contribute to the occurrence of the disease, for the further development of the pathological process causative factor not required (eg radiation sickness or burns). IN otherwise pathogenesis develops as long as the causative factor acts on the body, for example, during infections. Possible and longer-term action of the causative factor, when agents that cause diseases remain in the body longer than pathogenesis lasts (for example, this is observed with bacterial carriage).
2. The role of the reactivity of the organism itself during the development of the corresponding pathological process in it. So,

The pathogenesis of the disease includes two parts: pathological changes in the body and protective adaptive reactions to exposure to a harmful factor. The body develops adaptation and compensation processes that ensure the restoration of homeostasis (stability of the internal environment).

3. The role of general and local changes in the body that arise as a result of the development and spread of the pathological process.

4. The role of specific functional and morphological changes in the development of the disease.

5. The significance of certain changes in the nervous system as a result of the development of the disease.
When studying pathogenesis, it is first necessary to determine the main link in the development of pathology. If it is eliminated, further development of the disease is impossible. For example, in diabetes mellitus, the main pathological link is insufficient insulin production. If this hormone is administered externally, the patient does not develop other symptoms of this disease.

In pathogenesis, local disorders primarily develop, which can cause changes at the organism level. Thus, inflammation is a local lesion, but over a long period of time it causes a general reaction – fever. Structural changes lead to functional disorders, and functional disorders can cause structural changes, therefore any pathological process includes a whole complex of reactions that are interrelated and generally create a holistic picture of each disease.

The term "etiology" comes from the Greek. aitia – cause and logos – reason, teaching and is literally translated as the teaching about the cause of illness. Today, the concept of etiology has a broader meaning - an idea of ​​the causes and conditions of the disease. The validity of this interpretation of the term will become clear from the further presentation.

There are general and private etiologies. General etiology is a branch of pathophysiology that studies possible reasons and the conditions for the development of any disease - disease in the collective meaning of the word, disease as the main category of pathology. Particular etiology concerns the causes and conditions for the occurrence of a specific disease (malaria, typhoid fever, burns, frostbite, radiation sickness etc.) and is part of clinical disciplines.

The cause is called the factor disease-causing and imparting to it fundamental, as a rule, specific features, without whose influence the disease is impossible. For example, the cause of burns is heat, radiation sickness - ionizing radiation, infectious diseases - microbes, viruses, (tuberculosis bacillus - the causative agent of tuberculosis, pallidum spirochete - syphilis, adenovirus - acute respiratory infection, hepatotropic virus - hepatitis, etc.). There are polyetiological diseases that can develop under the influence of not one, but several equivalent causes. Such diseases include tumor disease, the causes of which, according to modern concepts, can be chemical, physical carcinogens and oncogenic viruses (see the chapter “Tumors”).

There are external (exogenous) and internal (endogenous) causes of the disease. Exogenous include: chemical (poisons, toxins, alkalis, acids, etc.), physical (mechanical, thermal, radiation, electrical effects, etc.), biological (action of microbes, viruses, protozoa, fungi, damage caused by animals) and social factors, including factors of information nature. Endogenous causes associated with heredity, constitution, etc.

Factors of a nature unusual for the body, which it does not encounter in everyday life (virulent microorganisms, toxins of poisonous snakes, insects, other poisons, electric current, etc.), as well as familiar factors, which, however, differ in their unusual strength or duration of action (extremely high or low temperatures, barometric pressure, a sharp deficiency or excess of oxygen, mechanical, sound exposure that is excessive in intensity or duration, emotional stress, etc.) are called pathogenic or pathogenic. Adaptation to the action of such factors is impossible or requires special conditions (training, hardening, vaccination, etc.).

In some cases (with altered reactivity of the body), a pathogenic effect that develops according to the principle unconditioned reflex, and conditionally reflex, can be achieved under the action of ordinary, indifferent stimuli. For a person who has a second signaling system, such a conditioned stimulus is often a word.

The cause of a large group of so-called hereditary diseases are various types of defects in the genetic apparatus.

This means that not everything is not always determined by the stimulus. Along with the cause of the disease in its occurrence and development important have conditions that both promote and hinder this. They, in turn, can be external and internal. Unlike the cause, conditions are not necessary for the development of the disease, and in each specific case the combination of causes and conditions may be different.

Sometimes the same factor in some cases, with one degree of severity of its action, can act as the cause of the disease, in others - as a condition favorable to the development of the disease. For example, nutritional deficiency (protein, vitamin) serves an important condition, contributing to the development of many different infectious and non-infectious diseases infectious nature. It can also be the cause of independent diseases, characterized by certain symptoms specific to each of them. Thus, prolonged malnutrition with a predominant lack of protein substances in food leads to the development nutritional dystrophy, chronic combined deficiency of vitamins C and P causes scurvy, vitamin B1 deficiency - severe polyneuritis - beriberi disease, etc.

Factors contributing to the occurrence of diseases include: malnutrition (both in the direction of malnutrition and overeating), hypothermia or overheating, high air humidity, rapid changes in temperature, atmospheric pressure, significant air speed, fatigue, previous diseases, hereditary predisposition, pathological constitution (diathesis), early childhood and old age, etc. For a person, a special role is played by the social environment, associated with the conditions of his life, information overload, so characteristic of modern man, housing and material insecurity, industrial and family troubles, criminalization of society, wars, terrorism, consequences of natural disasters, etc.

As an example of conditions that prevent the development of the disease, one can name a balanced diet that is sufficient in quantity and calorie content, a properly organized working day, training, and hardening. Hereditary, racial and constitutional factors are important, namely species immunity (a person does not suffer from canine and cat distemper; viral hepatitis, on the contrary, only a person is sick, in natural conditions no animal species is immune to it), hereditarily determined resistance to certain species pathologies (people suffering hereditary disease sickle cell anemia, as a rule, do not suffer from malaria), etc.

Thus, etiology should be understood as both the cause and the entire complex unfavorable conditions(external and internal), in the presence of which the cause can manifest its pathogenic effect and cause the development of the disease.

This understanding of etiology did not develop immediately. At least three alternative positions can be distinguished.

As you know, the second half of the 19th century was marked by the discovery of more and more new microorganisms - causative agents of various infectious diseases. Gradually, the impression developed that each disease was caused by its own pathogen, its own specific causative factor. The situation involved in the occurrence of the disease was considered extremely simply, according to the formula “cause – disease”. This is how the first direction in etiology emerged, called mono-causalism (mono - one, causa - cause). However, information gradually accumulated that, firstly, such a simple formula is not always implemented. The interaction of the pathogen and the organism does not always lead to disease. Let's take, for example, cases of bacilli carriage: the cause - the causative agent of typhus, cholera, diphtheria, polio - is present, but the disease is absent. It is known that 95% of people in childhood are infected with the tuberculosis bacillus, but the disease occurs in only a portion of them. On the other hand, a combination of a number of unfavorable conditions can significantly change the body’s resistance or sensitivity to the effects of the same pathogen. And not all diseases are caused by microbes or viruses. The position of monocaugalism has significantly weakened. It is being replaced by a new concept - conditionalism (condicio - condition), according to which disease is the result of the interaction of the body with a complex of a number of unfavorable conditions - fundamentally equal and necessary for its development. Otherwise, there is not and cannot be any specific cause of the disease, all factors are equal, everything depends on their combination, each factor can be decisive. Conditionalism became widespread and was dominant among physicians in many countries for quite a long time.

Criticism of monocausalism resulted in the emergence of another direction in etiology - constitutionalism, whose supporters, unlike supporters of monocausalism and conditionalism, who ignored the role of the organism itself in the development of the disease and, in particular, the role of heredity, exaggerated the constitution, without attaching any significant importance to microbes nor any other factors external environment.

Recognizing the undoubted importance in the occurrence of a disease of the hereditary properties of the body, which invariably act on it in various combinations, numerous diverse, including unfavorable environmental conditions, one should still remember that tuberculosis is caused by the tuberculosis bacillus and is impossible without its presence, as well as without excessive irradiation (α-, β-, γ-, x-rays) radiation sickness does not occur. Otherwise, the above definition of etiology, which takes into account both the cause and the conditions favorable to its implementation (external and internal), more successfully reflects reality.

At one time Z.G. Frenkel and G.L. Luban proposed a classification of etiological factors of the disease, taking into account the characteristics of the stimulus, the properties of the body (reactivity) and possible mechanism his response (Table 1). In the classification, in addition to the generally accepted division of stimuli into pathogenic and indifferent, psychogenic is conventionally distinguished, selectively acting only on a person, his psyche, the response to which is mediated through a second signaling system.

Table 1

Today, the table has been supplemented with another irritant, conventionally called “genetic,” which emphasizes the direction of its action and the mechanism of implementation. Without claiming to be the ultimate truth, the table clearly reflects modern ideas about possible results relationships and interactions between the external causal factor and the organism.

Pathogenesis (from the Greek Pathos - suffering and qenesis - origin) is the doctrine of the mechanisms of occurrence, development and outcome of the disease.

As well as etiology, pathogenesis is divided into general and specific. The section of pathogenesis, which includes consideration of the general patterns of formation and development of any disease, regardless of its nosological form, is called a general pathogen. Its main provisions are studied at the Department of Pathophysiology. Particular pathogenesis concerns specific development mechanisms certain disease and is considered in the study of various clinical disciplines.

The provisions of general pathogenesis are based on information obtained from studying the mechanism of development of individual nosological forms of diseases (particular pathogenesis), and are the result of their generalization and critical analysis, taking into account the fundamental principles of theoretical biology and medicine. In turn, the provisions of general pathogenesis are used when interpreting data obtained during the study of the mechanisms of development of specific diseases, to understand the possible features of their course.

The role of the etiological factor in pathogenesis .

The etiological factor acts as a trigger factor for the disease. Its pathogenesis begins with damage, breakage, pathological reactions, which in turn initiate according to the principle of a reflex, and also due to hormonal influences inclusion and formation of compensation processes.

In a number of cases (when the body is exposed to high and low temperatures, electric current, mechanical trauma, etc.), the role of the etiological factor (as the primary trigger) ends here. Further development The process occurs through a cascade of phenomena determined by cause-and-effect relationships. In most forms of pathology (hereditary diseases, poisoning with poisons, toxins, salts of heavy metals, most infectious diseases, etc.), the etiological factor acts for a long time, sometimes throughout the entire process, determining the essential features of its pathogenesis.

Thus, there is a close connection and interaction between etiology and pathogenesis, but it retains its own individuality, its independent significance in the development of the disease. In this regard, the term “etiopathogenesis” should be considered inappropriate, implying the merging and leveling of differences between etiology and pathogenesis.

relationships and vicious circles

Pathogenesis can be divided into many stages or links, interconnected by cause-and-effect relationships. Changes that occur during the development of the disease become triggers for new disorders. In this case, relationships can develop not only in a straight line, but also acquire the character of a circle. The development of cause-and-effect relationships in a straight line and the formation of “vicious circles” can be traced using the example of the mechanism of development of shock. With extensive trauma, accompanied by the development of shock, a huge mass of nerve receptors is irritated extremely strongly, long acting irritant. The associated unusually powerful flow of centrifugal impulses (primarily pain) causes phase changes in the cells of the central nervous system, the second stage of which is characterized by generalized inhibition of the cortex and subcortical centers of the brain. Inhibition of the vasomotor center is accompanied by a sharp drop in arterial blood pressure. blood pressure, and as a consequence of this, significant tissue hypoxia, including brain tissue. The latter, in turn, deepens the inhibition of the cortex and subcortex, and, therefore, leads to a further, even more significant decrease in blood pressure with all the ensuing consequences. More detailed information about cause-and-effect relationships and the formation of vicious circles during shock is given in the chapter “Extreme Conditions”.

The role of the leading link in pathogenesis

It is important to determine the leading link in the chain of phenomena that arise during the development of the disease. Thus, impaired insulin production due to insufficiency of the islet apparatus of the pancreas serves as the main link in the chain of disorders characteristic of diabetes mellitus. The leading link in the development of severe (without treatment - fatal) anemia in Addisson-Biermer disease is a deficiency of vitamin B 12 due to impaired absorption due to genetically determined insufficiency of the parietal glands of the stomach, which normally produce gastromucoprotein, which ensures the absorption of vitamin B 12 in the intestine. Impact on the main link (in our examples, parenteral dosed administration of insulin in the first case, vitamin B 12 in the second) allows you to break the chain and achieve a therapeutic effect.

pathogenesis

Genesis origin, origin)

a set of processes that determine the occurrence, course and outcome of diseases. The term “pathogenesis” also refers to the study of the mechanisms of development of diseases and pathological processes. In this doctrine, a distinction is made between general and particular P. The subject of general P. is the general patterns inherent in the main features of any disease process or individual categories of diseases (hereditary, infectious, endocrine, etc.). Particular P. explores the mechanisms of development of specific nosological forms. Ideas of general P. are formed on the basis of the study and generalization of data on the mechanisms of development of individual diseases, as well as on the basis of the theoretical development of philosophical and methodological problems of general pathology and medicine in. At the same time, the doctrine of general P. is used in the study and interpretation of the mechanisms of development of individual specific diseases and the characteristics of their course.

The study of P.'s disease is based on the analysis of clinical data, the results of a variety of laboratory, electrophysiological, optical, radiological, morphological and many other research methods, including various functional tests and treatments. Various forms of modeling pathology on living and nonliving objects, as well as mathematical and cybernetic methods, are of great importance for the study of both the general laws of P. diseases and the mechanisms of individual diseases and pathological processes.

Pathogenesis largely depends on etiological factors. In some cases, the action of the etiological factor throughout the entire disease process decisively determines its P. (for example, in most infectious diseases, many intoxications, hereditary diseases, some endocrine disorders). In other cases, the primary impact of the etiological factor is only a trigger in the chain of cause and effect. Each link in this chain becomes, in turn, an etiological factor in the natural development of subsequent phenomena, i.e. pathogenesis of the disease process, even in the absence of its root cause. In some cases, P. is characterized by the appearance of a so-called vicious circle. Thus, of any origin (for example, circulatory), having reached a certain degree, leads to disruption of other parts of the oxygen transport and utilization system (for example, the respiratory center). The resulting alveolar aggravates the severity of the hypoxic state, which, in turn, causes further hemodynamic disorders, worsening hypoxia, and even greater respiratory failure. The specific structure of the vicious circle may be different, but once it occurs, it usually seriously aggravates the course of the disease process, often creating life-threatening situations. The problem that arises is often eliminated only with external intervention.

The nature and significance of etiological factors in the development of the disease at its different stages can change many times. Due to the presence of a dialectical relationship between the categories of etiology and pathogenesis, the term “” appeared in the medical literature, but it was not widely used.

The ratio and significance of local and general processes in P. is variable. Thus, with inflammation (Inflammation) caused by local tissue damage, it develops mainly in the area and is aimed at limiting the source of alteration, destroying or removing the damaging factor, products of cell destruction and compensation of the local tissue defect. General changes in the body are in most cases relatively minor. In other cases, small-scale local disturbances through receptor and neurogenic mechanisms or humorally (as a result of a lack or excess of biologically active substances) cause pronounced generalized reactions. Examples of this include cholelithiasis and kidney stones, a limited inflammatory process that, as a result of severe painful stimulation, entails a whole chain of reactions. local processes may be associated with the physiological significance of the damaged structures responsible for the vital functions of the body, for example, the respiratory center or the conduction system of the heart. Along with this, local pathological changes in various organs and systems can occur secondarily as a result of primary generalized processes (for example, the kidneys during general intoxication). The area of ​​secondary local damage depends on many factors: the specific tropism of pathogenic agents to certain tissues, the routes of their elimination, and the biological characteristics of the damaged structures. Individual morphofunctional characteristics of the body, depending on its constitution (Constitution), previously suffered diseases and other factors that determine the reactivity of the body and the reactive properties of its individual organs, tissues and systems, can be of great importance in the localization of pathological processes.

With the development of any disease, as a rule, nonspecific and specific P mechanisms are detected. Nonspecific mechanisms are typical pathological processes, for example, fever, as well as so-called elementary processes, for example, increased permeability of biological membranes, changes in membrane potential, reactive oxygen species, etc. An example specific mechanisms may be activation of cellular and humoral immunity systems, hormone receptor interactions. However, an alternative distinction between P.'s mechanisms into specific and nonspecific cannot be carried out consistently. Thus, inflammation and fever in each specific case may have a number of characteristic distinctive features, and at the same time, highly specific immune processes contain a number of common features.

Among the various mechanisms of disease development, the most significant ones are identified, which are constantly encountered in a given disease and determine its main features. These mechanisms are usually called the main links of pathogenesis. Such a main link, for example for acute blood loss in the initial stage, is a decrease in the volume of circulating blood and circulatory hypoxia. At later stages, after replenishment of blood volume due to tissue fluid and renal water retention, the leading link of P. becomes, accompanied by hypoproteinemia and hemic hypoxia. After restoration of blood proteins, hemodilution erythropenia remains the main element of the posthemorrhagic state for some time. Thus, as the disease process develops, the leading links of P. may change. It often turns out to be impossible to single out from many pathogenetic factors a single one - the main or leading one, even taking into account the stage of the disease.

The occurrence, development and completion of a disease in the vast majority of cases consist of processes that are dual in their biological essence and significance for the body. P. includes a direct consequence of the action of a pathogenic factor (primary or disorder), structural and functional disorders that arise secondarily during the disease process, and, simultaneously or with a certain shift in time, the formation of protective-adaptive (sanogenetic) reactions aimed at preventing or eliminating pathogenic effects and emerging disorders in the body. The triggering mechanisms for these reactions can be the factor itself, as well as the primary and secondary results of its damaging effects. Both primary and secondary disorders, and protective-adaptive reactions can be realized at various levels - from molecular to organismal, including behavioral reactions.

When assessing individual components of P., a discrepancy often arises between their potential and actual value for the body. For example, inflammation, the most important protective process in nature, under certain conditions can have harmful and even disastrous consequences for the body. The actual significance of individual elements of inflammation - venous hyperemia, increased permeability of blood vessels, exudation, etc. - may also be different. In some cases, the same effect on the influence of a pathogenic factor simultaneously has both positive and negative significance. Thus, the adductor arterioles of the renal glomeruli during acute blood loss help maintain central hemodynamics and water retention in the body. However, at the same time it has a biologically negative meaning, because disrupts excretory function; In addition, intensive and prolonged renal damage can lead to their degeneration and severe renal failure.

Bibliography.: Ado A.D. Questions of general nosology, M., 1985; Anokhin P.K. Essays on the physiology of functional systems. M., 1975; Davydovsky I.V. General human, M., 1969; Methodological problems of medicine and biology, ed. D.K. Belyaev and Yu.I. Borodina, Novosibirsk, 1985; General human pathology, ed. A.I. Strukova et al., book. 1-2, M., 1990; Petlenko V.P. Philosophical questions of the theory of pathology, book. 1-2, L., 1968-1971; Petlenko V.P., Strukov A.I. and Khmelnitsky O.K. and theory of causality in pathology, M., 1978; Tsaregorodtsev G.I. and Petrov S.V. The problem of causation in modern medicine. M., 1972.

1. Small medical encyclopedia. - M.: Medical encyclopedia. 1991-96 2. First aid. - M.: Great Russian Encyclopedia. 1994 3. encyclopedic Dictionary medical terms. - M.: Soviet Encyclopedia. - 1982-1984.