The pathogenesis is a set of sequential processes determining the mechanisms of occurrence and course of the disease. Pathogenesis includes interrelated processes of the sick organism (physiological, biochemical, morphological, immunological and so on), developing in him after exposure etiological factor (see Etiology). For example, if you burn the etiological factor is the effect on the skin or mucous membrane heat, and then develops the disease process, including the changes in the nervous and vascular systems of the burn and throughout the body (at a sufficiently large damage), metabolism, and so on, which may last a long time.
Thus, pathogenesis is an effect caused by this or that reason (aetiological agent). There are diseases polietiologic, but monopolisation and, on the contrary, monoethylamine, but with different pathogenesis. In the first case, various external agents can cause similar or even the same pathological process, in the second - the same causal factor in different conditions, or if different individuals entails the development of different intensity and character of pathological reactions.
Pathogenic effect causes the body two kinds of reactions: "Paloma" (damage) and protection. "Floors" depends on the influence of etiological agent and usually represents only damage. An example of such damage can serve necrosis from burns, broken bones as a result of injury, etc.
Other kinds of reactions, occurring in a sick body that are protective, compensatory. They increase the body's ability to withstand the harmful influences of pathogenic factor and to compensate for the damaging action or to restore the damaged functions. So, when bleeding, leading, in particular, to the lack of oxygen in tissues, increases lung ventilation, increased heart rate, a number of reflex reactions causing the increased supply of oxygen; activates blood-forming function.
The unity of the phenomena of damage and protection and represents the pathogenesis of a pathological process, and therefore the pathogenesis follows sanogene - a set of reactions, leading to recovery.
However, in some cases, protective reactions, growing quantitatively in the disease process, can become pathological reactions. So, the inflammation in the eye, resulting from contact with him, even the smallest foreign body that can lead to blindness, although this inflammation is defensive in nature and is aimed at the removal or destruction of a foreign body.
Thus, the nature of pathogenetic reactions depends, on the one hand, the intensity of the etiological factor (for example, a higher dose of ionizing radiation causes more severe radiation sickness), on the other - from the reactivity of the organism (see).
Of great practical importance of studying the pathogenesis of the disease is that, knowing him, it is possible to purposefully and, therefore, to effectively influence on one or another process using therapeutic or surgical interventions. Modern therapy took a step forward from symptomatic (directed against individual symptoms) to the pathogenetic acting directly on the physiological, biochemical and immunological processes that underlie detectable symptoms. Such therapy has two objectives - elimination of corruption and activation (within certain limits) protective mechanisms (see the resistance of the organism).
In the pathogenesis of participation of all systems of the organism; an important role is played by changes in the nervous and endocrine systems, not only in the case of nervous and mental or endocrine diseases, but also in the development of most other diseases. An example is hypertensive or ulcers in the pathogenesis of which the leading role is played by disorders of the nervous system.
The violations in pathological process, occurring not only at the level of the entire organism and various physiological systems, but also on the cellular, sub-cellular and molecular levels.
In its time the pathogenesis imagined as an abnormal condition and liquid environments of an organism - blood and interstitial fluid. This theory, called the theory of "humoral pathology", now disproved, and has only historical value.
The study of pathogenesis allows not only to clarify the mechanisms of emergence and development of the disease, but also reasonable to treat her.

Pathogenesis (from the Greek. pathos - suffering, illness and genesis - Genesis - a branch of medicine dealing with development issues as private pathological processes and diseases in General. The pathogenesis is responsible, therefore, to the question, how is the process, implying the need for the study of all biological mechanisms of this process (physiological, biochemical, morphological, immunological and so on).
This allows us to distinguish the pathogenesis from the concept of etiology (see), which is embedded in the study of the collection primarily external damaging factors affecting the body. Etiology, therefore, answers the question what caused this or that pathological process. Studying P., we understand the essence of the process, its content, its dynamics. Skin burns red-hot subject (etiology) determines the development of the burn process, P. which is characterized by the involvement of the nervous and vascular systems, humoral and metabolic factors through closer involvement of the cellular and non-cellular structures. This development will go in one direction or another defined rate in relation to change some private other symptoms. Only the first link of this vzaimosoedinenii system of private processes that occur after the burn, directly linked to the etiology of the process (burn). Further links are associated with these causal factors only indirectly. The moment burn covers a fraction of a second; the pathological process, followed by the next, lasts for days or weeks and develops according to the principle of self-development, or motion. This is the guiding principle of pathogenesis.
This principle implies the other, no less important,is the change of cause-effect relations, which determines the change in the biological significance of chain reactions.
In other words, all the pathological processes are a product of evolution. They reflect the historical past of the animal world, adjoined over millions of years with various pathogenic factors of external environment (trauma, parasites, bacteria, and so on). The body responds to these factors reactions, formed in the distant past, and the more difficult external environment in which an organism lives, the more difficult and the mechanisms underlying these reactions.
In the pathogenesis we see the action or the result of some reasons. Mapping P. this leads to an important conclusion: causes, i.e. environmental factors, not necessarily equal to the action. One reason may cause different effects and different reasons - one and the same action. So, on the place of burning, as a rule, it causes inflammation ending the healing of the defect. And inflammation, and healing have its own laws of development, its pathogenesis. But in some cases, followed by burns can develop shock, tetanus, duodenal ulcer, and in the outcome of the healing of cancer. All these processes have already new mechanisms. The reason (burn) is, therefore, not equal action. This is the second very important regularity in Petrograd, and at the same time and in the doctrine of etiology.
This same trend can be observed in cases where the causal factor is invalid. The infected organism may not get sick, exposure to a carcinogen ineffectual. In such cases, the reason is not only not equal action, but the action is absent due to the fact that in the organism there are no pathogenic mechanisms, adequate exposure, or, on the contrary, there are mechanisms, opposing this impact. These are the mechanisms of innate and acquired immunity (see). If grease rabbit ear carcinogen, in 1-2 months. on the spot lubrication will have cancer, that is the pathological process with its own mechanisms of development. Similar experience, set on a Guinea pig, fail (and in rabbits). This means that Guinea pigs carcinogen oppose any mechanisms cancelling this action, or the substance is not a carcinogen in animals of this species.
The experiments showed that the pathogenesis of cancer (his intimate physiological and biochemical mechanisms) is not conditioned by the presence in the growing tumor viruses or carcinogens with a variety of physical and chemical properties. P. how would undermine this diversity of carcinogens, bringing their action to a common denominator, that is, to cancer. It does not follow that causative factors always otlichayutsya in Petrograd On the example of various infectious diseases (and abdominal typhus fever, pneumonia, malaria, and so on) can be shown that, in accordance with the pathogen in the pathogenesis include specific body systems and, moreover, in a different sequence, with different localization occurring in these systems processes. Clinical and anatomical symptomology of infectious diseases will reflect the participation of these systems (nervous, cardiovascular, and so on) in paragraph (Thus, for example, infectious diseases revealed closer connection with P. etiological factors, their unity. Very often in Petrograd there are presents not so much specific as individual acquired or congenital features of functional systems of the body. These are allergic reactions (see Allergy), Haemophilus bleeding case of a minor injury (see Hemophilia), etc.
The study Ii. has the big practical value. Knowing the pathogenesis of the disease can be successfully intervene in its development, breaking those or other elements of the process with the help of chemotherapy drugs, antibiotics, operational activities and other Modern therapy is mainly pathogenetic, pursuing a task or stop the development process, or change in the favorable direction of its flow.
The most important mechanisms of development of pathological processes laid down in the nervous, vascular, endocrine system, in the system of connective tissue, blood. In fact, however, the physiology, the systems, all structural levels (from the molecular to the whole body), the entire "genetic resources" are somehow involved in Petrograd, stimulating, suppressing or that particular side of the process or modeling it. Neurogenic mechanisms, both Central and peripheral underlie not only the nervous and mental diseases, but also diseases of other body systems, particularly the heart, blood vessels. An example of this can be angina, hypertension. The autonomic nervous system is crucial in the development of vasomotor and secretory, exchange and other disorders. The huge role played by hematogenous, lymphogenous mechanisms, such as spread by blood or the lymphatic system microorganisms, cancer cells, the formation of metastases. Mechanism of allergic reactions due to the binding in certain tissues of antigens and antibodies, resulting astrometrically processes, vasomotor disorders in various organs of the body (lungs, liver, kidneys, brain, skin, and so on). At the same mechanism include altered tissue sensitivity (to the antigen, the allergen), their special irritability, i.e. a factor of sensitization.
An important place among the mechanisms of pathogenesis take excretory processes, pathogenic when the start (poison toxin, allergen, a microbial pathogen of infectious diseases) is allocated by various systems of the body, changing the internal environment of these systems, their exchange, secretory and motor reaction, and this raises the processes of different localization and intensity. So, in the administration of mercuric chloride excreted by the kidney albuminates mercury causes serious changes in the nephrons. When kidney failure nitrogenous waste products strenuously allocated mucous membranes of the gastrointestinal tract, respiratory tract, skin, serous membranes, leading to the development of uraemic gastroenterocolitis, bronchopneumonia, pericarditis, etc., the Accumulation of salts in the blood calcium and risks deposits of these salts in different organs of the body (lungs, stomach, artery). Changes of solubility of inorganic and organic compounds, such as bile pigments, cholesterol, urate, are the basis of certain forms stone disease (biliary tract, urinary tract). Changing the solubility of blood gases (nitrogen, oxygen) is the basis of the pathogenesis of decompression sickness.
Great importance in the pathology received mechanisms that alter the permeability (see, for example blood vessels, for proteins, lipoproteins, mucopolysaccharides, water, salt. These include the problem of atherosclerosis, the problem of swelling of the different Genesis.
Pathogenetic mechanisms develop not only on the level of Fiziol. systems of the body, but also at the levels of cellular, sub-cellular and molecular. Histo - and cytochemical, electrophysiology and electron microscopic studies reveal specific changes in cell membranes, organelles in the cytoplasm (the mitochondria, endoplasmic network, the Golgi apparatus, and others). Of great importance are the different changes in the permeability of cell membranes, the expression of enzymes in the cytoplasm and in the environment. Essentially these changes at the cellular and molecular levels, including intercellular fibrous structure, the basic substance, define the final result of the actions of those or other mechanisms. This applies to neurogenic mechanisms of the Central and peripheral Genesis, because lability of receptors and effectors in the organs of the body is closely connected with the specific substrate of these bodies, with their "functional proteins"; the latter are those representatives of the elementary forms of stimulation, which determine ultimately the effect of irritation in physiology and pathology.
Cm. also the Disease, the Reactivity of the organism, the organism Resistance.